This patch fixes some issues caused by design issues in video4linux, adds some nicety...

This patch fixes some issues caused by design issues in video4linux, adds some nicety to video4linux2 plugins and doe...

Original commit message from CVS:
This patch fixes some issues caused by design issues in video4linux, adds
some nicety to video4linux2 plugins and does some more evil stuff:
* video4linux doesn't tell us which formats are supported by a card, so
the only way to know this is by simply trying it out. This patch adds that.
* v4lmjpegsink didnt have a bufferpool yet - is integrated now.
* all copy() bufferpool functions have been removed since they're not needed.
* v4lmjpegsink doesnt have a free() function, because hen playing the frames,
all this is already handled. When the frame is not played, nothing has to
be done. In total, the function is not needed.
* adds a get_caps() function to v4l2src
* some minor crap