skins2: update documentation with new features for vlc1.1 and vlc1.2

skins2: update documentation with new features for vlc1.1 and vlc1.2

These features include

for vlc11
 - new variables : vlc.canRecord and vlc.isRecording
 - new functions : vlc.toggleRecord() and vlc.nextFrame()
 - a new 'loop' parameter for animated bitmaps
 - a special id="fullscreenController" for Window, intended to be
   used as a skinnable fullscreen controller

for vlc12
 - a new 'art' parameter for image control
 - a new 'scale2' value for resize parameter of image control