svn merge ^/trunk/blender -c56907 -c56908

Fix for last fix, compile error in smoke code.

Fix #35407: different particle behavior compared to 2.66, reverted part of 56073.

Painting / Sculpting: more tweaks to pressure sensitivity

* Also do pressure interpolation for brush size and spacing.
* Do smoothing of pressure when smooth stroke and sample average is enabled.
* Revert the OS X specific pressure change to pressure ^ 2.5, for low pressure
values like 0.05 it makes the pressure 100x lower, which is problematic. If
we need to adjust the pressure curve it should be done for all platforms.

Still weak:

* Pressure of first touch on tablet is difficult to control, usually it's low
which makes the stroke start out small or soft, but other times not. Finer
event capturing at ghost level would help, along with pressure changes without
mouse movement, but this may also need different paint stroke logic.
* Brush radius is rounded to integers, this gives noticeable stepping.
* Brush falloff is not antialiased, gives noticeable aliasing for small brush
sizes which was always a problem, but is more common with size pressure control.

Fix #35390: sequencer end frame of preview range was not drawing correct.

Fix #35404: crash in file save with python code that accesses mesh from panel.

On file save the mesh gets loads from the editmesh but the derived mesh caches
wer not cleared. This usually happens through the depsgraph but it needs to be
done manually here. Most changes are some refactoring to deduplicate derived
mesh freeing code.

Fix for #35390 fix: sequencer scene start/end still did not display when they are equal.

Fix #35390: the verticel lines indicating scene start and end frame in the
sequencer now draw such that a strip that spans this time is contained just
between these lines.

Fix #35398: changing render layer name causes animation to be lost.

svn merge ^/trunk/blender -c56851