Switch package file accessor classes to use BPositionIO

* PackageFileHeap{Reader,Writer} as well as Package{Reader,Writer} and
their implementation and super classes do now internally use a
BPositionIO instead of a FD to access the package file. This provides
more flexibility needed for features to come.
* BPackageReader has already grown a new Init() version with a
BPositionIO* parameter.

Switch package kit to BZlibCompressionAlgorithm

... and remove the Zlib{Compressor,Decompressor} API.

Remove BPackageKit::[...]::AbstractDataWriter and friends

* FDDataWriter and ZlibDataWriter weren't used anymore.
* AbstractDataWriter was implemented only by PackageFileHeapWriter,
which was only used by WriterImplBase.
* Add a PackageFileHeapWriter::AddDataThrows() which has semantics
equivalent to the previously inherited WriteDataThrows().

PackageFileHeapWriter: Fix update case

* Pull _UnwriteLastPartialChunk() out of Reinit() for reuse.
* _UnwriteLastPartialChunk(): fPendingDataSize wasn't set.
* _PushChunks(): Some simplifications for clarity.
* ChunkBuffer/RemoveDataRanges(): Use data reading and decompression
methods provided by our base class instead of duplicating the
implementation.
* RemoveDataRanges():
- _FlushPendingData() before starting, so we don't ignore the pending
data and _UnwriteLastPartialChunk() when done, so a partial chunk
is read back into the pending data buffer.
- fUncompressedHeapSize wasn't reset before the main processing loop,
thus resulting in an erroneous size later on.

Allow specifying the compression level for package creation

* Introduce BPackageWriterParameters which comprises all parameters
for package creation, currently flags and compression level. Such an
object can be passed to BPackageWriter::Init() and is passed on to
PackageWriterImpl and WriterImplBase.
* PackageFileHeapWriter: Add compressionLevel property and pass the
value on to ZlibCompressor.
* package add/create: Add options -0 ... -9 to specify the compression
level to be used.

hpkg format: compress the whole heap

Instead of handling compression for individual file/attribute data we
do now compress the whole heap where they are stored. This
significantly improves compression ratios. We still divide the
uncompressed data into 64 KiB chunks and use a chunk offset array for
the compressed chunks to allow for quick random access without too much
overhead. The tradeoff is a limited possible compression ratio -- i.e.
we won't be as good as tar.gz (though surprisingly with my test
archives we did better than zip).

The other package file sections (package attributes and TOC) are no
longer compressed individually. Their uncompressed data are simply
pushed onto the heap where the usual compression strategy applies. To
simplify things the repository format has been changed in the same
manner although it doesn't otherwise use the heap, since it only stores
meta data.

Due to the data compression having been exposed in public and private
API, this change touches a lot of package kit using code, including
packagefs and the boot loader packagefs support. The latter two haven't
been tested yet. Moreover packagefs needs a new kind of cache so we
avoid re-reading the same heap chunk for two different data items it
contains.

Switch package file accessor classes to use BPositionIO

* PackageFileHeap{Reader,Writer} as well as Package{Reader,Writer} and
their implementation and super classes do now internally use a
BPositionIO instead of a FD to access the package file. This provides
more flexibility needed for features to come.
* BPackageReader has already grown a new Init() version with a
BPositionIO* parameter.

Switch package kit to BZlibCompressionAlgorithm

... and remove the Zlib{Compressor,Decompressor} API.

Remove BPackageKit::[...]::AbstractDataWriter and friends

* FDDataWriter and ZlibDataWriter weren't used anymore.
* AbstractDataWriter was implemented only by PackageFileHeapWriter,
which was only used by WriterImplBase.
* Add a PackageFileHeapWriter::AddDataThrows() which has semantics
equivalent to the previously inherited WriteDataThrows().

PackageFileHeapWriter: Fix update case

* Pull _UnwriteLastPartialChunk() out of Reinit() for reuse.
* _UnwriteLastPartialChunk(): fPendingDataSize wasn't set.
* _PushChunks(): Some simplifications for clarity.
* ChunkBuffer/RemoveDataRanges(): Use data reading and decompression
methods provided by our base class instead of duplicating the
implementation.
* RemoveDataRanges():
- _FlushPendingData() before starting, so we don't ignore the pending
data and _UnwriteLastPartialChunk() when done, so a partial chunk
is read back into the pending data buffer.
- fUncompressedHeapSize wasn't reset before the main processing loop,
thus resulting in an erroneous size later on.

Allow specifying the compression level for package creation

* Introduce BPackageWriterParameters which comprises all parameters
for package creation, currently flags and compression level. Such an
object can be passed to BPackageWriter::Init() and is passed on to
PackageWriterImpl and WriterImplBase.
* PackageFileHeapWriter: Add compressionLevel property and pass the
value on to ZlibCompressor.
* package add/create: Add options -0 ... -9 to specify the compression
level to be used.

hpkg format: compress the whole heap

Instead of handling compression for individual file/attribute data we
do now compress the whole heap where they are stored. This
significantly improves compression ratios. We still divide the
uncompressed data into 64 KiB chunks and use a chunk offset array for
the compressed chunks to allow for quick random access without too much
overhead. The tradeoff is a limited possible compression ratio -- i.e.
we won't be as good as tar.gz (though surprisingly with my test
archives we did better than zip).

The other package file sections (package attributes and TOC) are no
longer compressed individually. Their uncompressed data are simply
pushed onto the heap where the usual compression strategy applies. To
simplify things the repository format has been changed in the same
manner although it doesn't otherwise use the heap, since it only stores
meta data.

Due to the data compression having been exposed in public and private
API, this change touches a lot of package kit using code, including
packagefs and the boot loader packagefs support. The latter two haven't
been tested yet. Moreover packagefs needs a new kind of cache so we
avoid re-reading the same heap chunk for two different data items it
contains.