Split up encoders sources.

Create a separate source / header file for each supported encoder and the base
class and rename classes for better readability. This should also make it
easier adding new encoders.

Remove a few trailing spaces while at it.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31592 a1c6a512-1295-4272-9138-f99709370657
14 files changed