packagefs: CachedDataReader: Don't implement ReadData()

It's already done the same way in the base class.

Remove BPackageKit::BDataOutput

Use BDataIO instead.

Revert "Move ZlibDecompressor to libshared"

This reverts commit 9af2105d36856be60528c361edf14a263f242338.

Conflicts:
src/kits/package/Jamfile

Move ZlibDecompressor to libshared

* This will be used to implement compressed http streams
* Remove the custom BDataOutput class, and use BDataIO instead, for
easier integration with existing code.

packagefs: Add caching for the package file heap reader

* ReaderImplBase:
- Add virtual CreateCachedHeapReader() which can create a cached
reader based on the given heap reader.
- Rename HeapReader() to RawHeapReader() and add HeapReader() for the
cached heap reader.
- Add DetachHeapReader() to allow a clients to remove the heap
reader(s) after deleting the ReaderImplBase object.
* packagefs:
- Add CachedDataReader class, which wraps a given
BAbstractBufferedDataReader and provides caching for it using a
VMCache. The implementation is based on the IOCache implementation.
- Use CachedDataReader to wrap the heap reader. For file data that
means they are cached twice -- in the heap reader cache and in the
file cache -- but due to the heap reader using a VMCache as well,
the pages will be recycled automatically anyway. For attribute data
the cache should be very helpful, since they weren't cached at all
before.

packagefs: CachedDataReader: Don't implement ReadData()

It's already done the same way in the base class.

Remove BPackageKit::BDataOutput

Use BDataIO instead.

Revert "Move ZlibDecompressor to libshared"

This reverts commit 9af2105d36856be60528c361edf14a263f242338.

Conflicts:
src/kits/package/Jamfile

Move ZlibDecompressor to libshared

* This will be used to implement compressed http streams
* Remove the custom BDataOutput class, and use BDataIO instead, for
easier integration with existing code.

packagefs: Add caching for the package file heap reader

* ReaderImplBase:
- Add virtual CreateCachedHeapReader() which can create a cached
reader based on the given heap reader.
- Rename HeapReader() to RawHeapReader() and add HeapReader() for the
cached heap reader.
- Add DetachHeapReader() to allow a clients to remove the heap
reader(s) after deleting the ReaderImplBase object.
* packagefs:
- Add CachedDataReader class, which wraps a given
BAbstractBufferedDataReader and provides caching for it using a
VMCache. The implementation is based on the IOCache implementation.
- Use CachedDataReader to wrap the heap reader. For file data that
means they are cached twice -- in the heap reader cache and in the
file cache -- but due to the heap reader using a VMCache as well,
the pages will be recycled automatically anyway. For attribute data
the cache should be very helpful, since they weren't cached at all
before.