The target "mediarepo-checkout" will use Subversion to checkout the raw
media repo.
The target "mediarepo-process" will process the previously checked out
media repo (copying and converting).
Ember code is adapted to handle both .png and .dds textures in some
cases.
Ember when built in non-release mode will automatically check the
locations of both the media repo (under the "mediarepo" directory in
source) as well as any processed media (under "ember-media-<version>" in
the build directory, and if detected load media from there, ignoring the
media installed in the installation prefix.
