Fix T41584: bpy.utils.time_from_frame out by a day

Fix from retroj
Correct docstrings
Cycles: Make Correlated Multi Jitter a regular feature.

It can be helpful in some cases and it works properly, so no need to hide it behind the experimental flag anymore. It's only enabled for the CPU though.
Rename drawnurb -> draw_editnurb

Since its only used for editmode drawing.
Fix T41574: Curve edit-handles draws in shadow

Also avoid redundant theme-color lookups
Fix T41568: Dissolve & Tear Boundary Keeps Verts
Comments
Cycles: Use compiler intrinsics for clz/ctz in CMJ code for MSVC
Fix T41355: Make-local looses linked modifiers texture
Fix T41590: When scene scale is not 1.0, and units are "None," Blender assumes translations are in meters.

Turned out there were several issues in handling of scale parameter by numinput.
Fixed that by factorizing more some code in common with 'usual' numbuttons eval code
(new `bUnit_getScaleUnit()` helper will return valid scaled value, depending on
given system and type).

Now, numinput behaves as expected - using default unit amended by scale in case no unit is given
(i.e. entering '20' with a scale of 0.01 will give you 20cm, and '20cm' as well!).
Move conditional out of loop since checked condition won't change
Move bUnit_getScaleUnit -> BKE_scene_unit_scale

unit.c intentionally doesn't include DNA or BKE headers (except its own)
Fix T37534 remaining issue: auto-enable bevel weight view
whenever enter edge bevel weight editing.

This is what happens when one makes an edge sharp, for instance.
The edge bevel weight display is not on by default for performance
reasons, but seems reasonable to enable it when user indicates
interest by editing bevel weight values.
Fix T38999: Tool tabs and Old Addons living in perfect harmony.

Just have a default 'Misc' category (harmless for panels in non-cat context).
In case we would still want a panel to show in all tabs (rather unlikely),
just explicitely give an empty string to its bl_category property.

Note I choose 'Misc' because it's much shorter than 'Uncategorized' (space
is an issue here), it's a one-liner to change it anyway if UI Mafia does not like it!
Update to 'Back to Black' theme.
Fix for broken hair sim in old files.

Files older than rB37e1285 have broken hair sim due to the (hacky)
velocity "damping" factor, which is not initialized to 1.
Fix T39020: Undo/Redo/History buttons missing in "Edit mode"

Remotely based on patch by kevindietrich (Kévin Dietrich), but using
a single generic panel here, as suggested by UI team.

Note we add this panel in all modes (only one tweak in scuplt mode,
where there is no history menu generated it seems, unlike other
'paint-like' modes), we can decide to move it into its own tab later.

Differential Revision: https://developer.blender.org/D733
Sculpt mode: fix 'stroke method' of Brush menu.
Cycles: Add an experimental CUDA kernel.

Now we build 2 .cubins per architecture (e.g. kernel_sm_21.cubin, kernel_experimental_sm_21.cubin).
The experimental kernel can be used by switching to the Experimental Feature Set: http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Experimental_Features

This enables Subsurface Scattering and Correlated Multi Jitter Sampling on GPU, while keeping the stability and performance of the regular kernel.

Differential Revision: https://developer.blender.org/D762
Patch by Sergey and myself.

Developer / Builder Note:
CUDA Toolkit 6.5 is highly recommended for this, also note that building the experimental kernel requires a lot of system memory (~7-8GB).
Add operator that deletes a texture paint layer for blender internal.