Now scrollbars correctly hide and show, making space for the actual contents
in a region. It solves several old hacks, and puts view2d code a bit more
back in control as well.
Implementation notes:
- The view2d mask feature is working again
- The #define V2D_SCROLL_HORIZONTAL_HIDE means: "turn on hiding".
- Code for UI_view2d_region_reinit() is enforcing better standard view settings
But... two hack/patches needed to be added:
- Region panel drawing: if after generating the button panels it appears
a scroller hides or reveils, it calls all the generating code again.
(a simple scale doesn't work due to rounding differences in layout code)
- View2d code that maps 'tot' and 'cur' rects: if this code detects that
the mask changes, it calcs the map code again.
Also a bugfix (issue in 2.65)
- The left/bottom area split widget was drawing 1 pixel too large sometimes,
leaving bad trails on moving area dividers.
Conversion from 2.49 and older files: support for unlimited materials on
objects had an error in conversion.
Effect was that you couldn't re-assign material slots a Material, in case
you were using "link to object" option.
The issue was caused by SEQ_BEGIN macro modifying sequence's depth
which ruined transformation routines. Used own DFS instead which
doesn't modify sequences.
Also corrected some typos in api and comments.
* Remove all code for Texture and Sequencer plugin system, this never worked in 2.5x / 2.6x and is therefore not needed anymore.
* DNA structures are kept, all read/writefile code is gone.
