r851: Merge 2.1:

r851: Merge 2.1:
Here is another load of small changes.
* The cursor handling was changed (it is hidden and shown at some places).
* Added some (currently dummy) arguments to functions in maincursor.C.
* AudioALSA::list_devices() now has an argument for selecting between
  recording and playback devices.
* Rounding error in picon drawing for long timelines fixed.
* Additional format presets.
* Assorted whitespace and code moving changes.
* An ID for resources is introduced.
* Implement render_stop() that cleans up after plugins (for live plugins).
* Moved video device creation from open_input() to new_device_base().
* VideoDevice::open_input() takes the frame rate as double instead of float.
* PictureConfig does not need an MWindow pointer, a BC_Hash* is enough.
* Remove video_is_on() and replace it by get_video_on().
and probably a lot more.

This revision should match GIT::3c7a200ee98947c540d802853ead4602d4f16574.