Switching to cmake.

A few notes:

1) I re-organized the directory structure in the process.

2) Archive plugin is not included for now. Major refactoring require for
archive plugins. Plan is to convert archive plugins to input plugins.

3) Eerything that does not have external dependencies are always
enabled. I've gone through the code, those features will not increase
the result executable size too much.

The conversion to cmake is considered done by now. Future changes will
be in separate commits.
cmake: Add check for Solaris
cmake: Add check for large file support
Remove check.h

Now all large file related definitions are included in CFLAGS.
Remove autogen.sh
cmake: Add compiler flags
cmake: Add zeroconf
cmake: Add sticker
cmake: Mark find_library result as advanced
Fix compiler warning
cmake: Always enable inotify when available
cmake: Add asap
cmake: Add mpcdec
cmake: Add wildmidi
playlist_control: Remove unnecessary assert

playlist_delete_internal may call playlist_stop when
there's no more track to play (i.e. playlist->current < 0).
And this will cause the assert to fault.
cmake: Update .gitignore