Move the skip-frame pref from video to codecs

This commit may eat your domestic pets.

Only import needed functions

(cherry picked from commit 8749a60070100b42765472bfef4be6e1fb1731e8)

Conflicts:

	projects/mozilla/vlcshell.cpp

(cherry picked from commit ce050593f3b4a668472d481154e1e548c1f79e03)

fix #3862

Use the same orange than in FFMPEG, instead of yellow.
It wasn't readable in consoles with white background.

It was possible with the oldtelnet interface using something like
(echo admin ; echo help) | nc localhost 4212
That's now working with the lua one (but not the cleanest way).

Also compare against RUNNING and not DONE on waiting loop. Also lock mainloop
when modifying values that are used in callback-code, and don't signal without lock.

 * Split the module source code into several files

Functionality is unchanged, but the result is more maintainable.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

This was cygwin specific, probably conflicting with ASLR/DEP
and noone is able to understand the logic behind it.

Close #3788