Blender Internal: Modify material property "Cast Buffer Shadows" to affect ray shadows also, and rename it to "Cast Shadows".

This allows us to make materials that don't cast ray shadows.
Turning off this property can reduce the rendering time slightly.

Note: RNA path is changed to "use_cast_shadows" as well. The older
path "use_cast_buffer_shadows" still can be used as its alias, but
it will be removed after updating some addons.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D272
Fix T38557: VSE clips with Alpha Over against a transparent background fail to reflect opacity changes
Bring back stabilization and GP panels to MCE
Fix T38574 uv sculpting cursor could be visible during render preview in
image editor.
Cycles: Clamp Direct now affects the Background too.

Reviewed by: brecht
Differential Revision: https://developer.blender.org/D306
Fix T38553: Crash load new level; array modifier using curve length

Since threaded object update we've disabled in-place
curve evaluation (in cases when applying curve modifier
with target curve non-evaluated yet).

This requires game engine to take care of DAG and object
evaluation (currently it's designed to export only objects
it able to render).

This workaround will make sure that curve_cache for curves
is up-to-date.
Own recent removal of string encoded menus missed render layers/passes
Fix Cycles Light Passes being always enabled, own regression in Clamp commit yesterday.

KernelIntegrator just doesn't have valid data at this point, so we need to go one level deeper.
Fix null-pointer dereference in previous sequencer commit
Better fix for T38501: blender crashes right after adding image texture to
material in cycles

Buggy MSVC 2008 in 32-bit mode ignores stack align attribute for float3.
Now it uses reference to __m128, which is always aligned.
Fix T38590: some material operators incorrectly appeared in the spacebar search menu.
Fix T38578: blender internal texture nodes + volume render error.
Fix T38547: crash in skeleton sketching.
Fix T38597: cycles status bar missing some updates.
Fix for fix with render layer menu
UI: change to give sliders more text space, messes with alignment
Mesh Data: disable two-sided for new meshes (see: T37518)
Cycles: Code refactor for Clamping/Inf Rejection, combined into 1 function. Also avoid some conditionals.

Reviewed by: brecht
Differential Revision: https://developer.blender.org/D310
Code cleanup: fix a few visual studio compiler warnings.
Cycles: mix hair minimum width code with SSE intersection code

Gives 6.5% speedup for hair.blend from testsuite.

This commit was previously reverted, but should work ok now. Patch by Sv. Lockal.