Interface / Modifiers: Don't show cage placeholder in modifier header, if the current modifier does not support it or the cage is disabled (like Subsurf 0).

This way we save some space but still avoid the jumping around while changing settings in the header itself.

Thanks to Brecht for help on this. :)
Fix T37811: Delete key shortcut missing for deleting markers

The keymap here used WM_keymap_verify_item(), which only allows for a
single hotkey to be bound to an operator. In most cases, this really
isn't justified.
Interface: Remove Play button from the Render panel, only keep in the "Render" menu.
Code cleanup: Remove Blender 2.4x animation player preset, since we have the internal one.
Interface / Modifiers: Use a toggle/icon button for vertex group invert (was already used in particle system).

This way we save a few lines of space, while keeping the functionality clear. Also some minor layout reshuffling and cleanup.
Code cleanup: Remove "TexFace to Material Convert", from the file menu. This was used for conversion from older 2.5x files. The do_version() code is still there and functioning though.
Merge branch 'master' of http://git.blender.org/blender