More functionality review fixes.

* Fix context issues with paint curve keymaps.

* Make paint curve cursor set operator modal.

Bring back select mouse tweak trasform, needed for image editor curves.

active pivot works in paint transform. It uses the centerpoint of the
last selected curve handle.

Paint Curves Transform:

* Cursor pivot working.
* Expose pivot in paint modes.

cursor transform WIP for curves

Use size for fixed length array args

Fix some undo issues with paint curves.

Fix issue with multiple materials not displaying colors correctly.

Finalize transform for paint curves:

Use own simple operator for slide transform, allows to return pass
through and set the cursor.

Cursor pivot not yet supported for paint curves, it will be next.

Make selection of paint curve handles much easier.

Themefy paint curve colors, some tweaks to make selected paint handles
more visible.

Functionality Review:

Fix: Rotating/Scaling a handle would not use curve center as pivot.

Functionality Review:

Bugfix: Paint curves not functioning in weight painting.

Palettes:

Functionality review:

Include "active palette color" concept, marked by triangular widget.
This is set when adding and selecting a palette color.
Add explicit delete operator that removes the active palette color.

Use BKE_libblock_find_name

Update factory defaults:

* Add mask and fill brushes to texture painting.
* Sculpt mode now has mirroring turned on.
* Lower default dyntopo resolution.
* Fill threshold not zero by default.

Paint Curves:

* Change behaviour of selection - selecting in empty space now will not
clear selection. This leads to:
* Improved behaviour of right click translate. Now even dragging in
empty space will drag correctly.

Minor edits, no point to using `short` for pixel coords

Was doing short/int/float conversion.
Also initialize on use

Merge branch 'master' into soc-2013-paint

Conflicts:
source/blender/blenlib/intern/math_vector_inline.c

Replace GSQueue with BLI_Stack for image filling

Was doing a malloc per pixel, and a redundant memcmp,
BLI_Stack chunks memory more efficiently.