Get test_app_server to run again

* We should have the buildbots compile this to make sure it still works
* I had to split two ServerApp methods to a searate C++ file to link
them in libtestappserver.so
* some fixes related to the switch to PM and better hybrid support in
jam rules; moving of MIME stuff from registrar to storage kit, merge of
Locale Kit and ICU in libbe, and a few more.
* Modified the test_app_server hwinterface and rdef file so it is not a
background app, and the window isn't floating. Otherwise, hiding the
window would leave you without a way to recover it.

registrar: Move more classes to libstorage_kit_mime.a

Move MimeSnifferAddon, MimeSnifferAddonManager, and TextSnifferAddon to
libstorage_kit_mime.a, so we can reuse them.

More work towards hybrid support

* All packaging architecture dependent variables do now have a
respective suffix and are set up for each configured packaging
architecture, save for the kernel and boot loader variables, which
are still only set up for the primary architecture.
For convenience TARGET_PACKAGING_ARCH, TARGET_ARCH, TARGET_LIBSUPC++,
and TARGET_LIBSTDC++ are set to the respective values for the primary
packaging architecture by default.
* Introduce a set of MultiArch* rules to help with building targets for
multiple packaging architectures. Generally the respective targets are
(additionally) gristed with the packaging architecture. For libraries
the additional grist is usually omitted for the primary architecture
(e.g. libroot.so and <x86>libroot.so for x86_gcc2/x86 hybrid), so that
Jamfiles for targets built only for the primary architecture don't
need to be changed.
* Add multi-arch build support for all targets needed for the stage 1
cross devel package as well as for libbe (untested).

Pull class MimeInfoUpdater out of UpdateMimeInfoThread

* Pull out base class MimeEntryProcessor out of AppMetaMimeCreator.
* Pull class MimeInfoUpdater out of UpdateMimeInfoThread and derive it
from MimeEntryProcessor.
* MimeInfoUpdater: Instead of BMimeType::GuessMimeType(), use
Database::GuessMimeType() directly.

Pull class AppMetaMimeCreator out of CreateAppMetaMimeThread

Instead of using a BMimeType to set the MIME type properties, it
operates directly on the Database object, though.

Refactor MIME DB access

* Add class DatabaseLocation. It contains a list of the MIME DB
directory paths plus methods to access type files.
* Move all low-level MIME DB access functions from
database_{support,access} to DatabaseLocation. All code that formerly
used those now requires a DatabaseLocation object. In BMimeType and in
the registrar the default object is used, but the low-level classes
can now be reused with different locations.
* Move get_icon_data() from database_access to database_support and
delete the former, which is now empty.

Move MIME DB code back from registrar to src/kits/storage/mime

* Together with database_{access,support}.cpp it is built into a static
library.
* Add new interfaces MimeSniffer and Database::NotificationListener for
plugging in registrar specific functionality (the sniffer add-on
support and the notification mechanism).

Get test_app_server to run again

* We should have the buildbots compile this to make sure it still works
* I had to split two ServerApp methods to a searate C++ file to link
them in libtestappserver.so
* some fixes related to the switch to PM and better hybrid support in
jam rules; moving of MIME stuff from registrar to storage kit, merge of
Locale Kit and ICU in libbe, and a few more.
* Modified the test_app_server hwinterface and rdef file so it is not a
background app, and the window isn't floating. Otherwise, hiding the
window would leave you without a way to recover it.

registrar: Move more classes to libstorage_kit_mime.a

Move MimeSnifferAddon, MimeSnifferAddonManager, and TextSnifferAddon to
libstorage_kit_mime.a, so we can reuse them.

More work towards hybrid support

* All packaging architecture dependent variables do now have a
respective suffix and are set up for each configured packaging
architecture, save for the kernel and boot loader variables, which
are still only set up for the primary architecture.
For convenience TARGET_PACKAGING_ARCH, TARGET_ARCH, TARGET_LIBSUPC++,
and TARGET_LIBSTDC++ are set to the respective values for the primary
packaging architecture by default.
* Introduce a set of MultiArch* rules to help with building targets for
multiple packaging architectures. Generally the respective targets are
(additionally) gristed with the packaging architecture. For libraries
the additional grist is usually omitted for the primary architecture
(e.g. libroot.so and <x86>libroot.so for x86_gcc2/x86 hybrid), so that
Jamfiles for targets built only for the primary architecture don't
need to be changed.
* Add multi-arch build support for all targets needed for the stage 1
cross devel package as well as for libbe (untested).

Pull class MimeInfoUpdater out of UpdateMimeInfoThread

* Pull out base class MimeEntryProcessor out of AppMetaMimeCreator.
* Pull class MimeInfoUpdater out of UpdateMimeInfoThread and derive it
from MimeEntryProcessor.
* MimeInfoUpdater: Instead of BMimeType::GuessMimeType(), use
Database::GuessMimeType() directly.

Pull class AppMetaMimeCreator out of CreateAppMetaMimeThread

Instead of using a BMimeType to set the MIME type properties, it
operates directly on the Database object, though.

Refactor MIME DB access

* Add class DatabaseLocation. It contains a list of the MIME DB
directory paths plus methods to access type files.
* Move all low-level MIME DB access functions from
database_{support,access} to DatabaseLocation. All code that formerly
used those now requires a DatabaseLocation object. In BMimeType and in
the registrar the default object is used, but the low-level classes
can now be reused with different locations.
* Move get_icon_data() from database_access to database_support and
delete the former, which is now empty.

Move MIME DB code back from registrar to src/kits/storage/mime

* Together with database_{access,support}.cpp it is built into a static
library.
* Add new interfaces MimeSniffer and Database::NotificationListener for
plugging in registrar specific functionality (the sniffer add-on
support and the notification mechanism).