Fix T37704: cycles hair render error with hair density vertex group.

Zero length hairs were causing problems, now it skips rendering them as they
are invisible anyway.
Fix T37713: proxy not updated for first frame in background render.

The problem is that the animation curves are first before object updates,
where BKE_pose_rebuild and proxy synchronize will undo the animation when the
proxy is evaluted for the first time after loading.

This is somewhat of a workaround but it's also useful to have the scene updated
once when opening in background mode, and it makes rendering from the UI and
background more similar and so more predictable to give the same result.
Minor fix to generated settings for scons (affected ilmbase/openexr).
Code cleanup: assign win size to const vars and some renaming
Fix incorrect comment - copy and paste error
Fix T37755: Autokey doesn't work for local Z-Axis in Camera view with MotionPaths enabled

The problem here was that the hack used to fix T24551 in r32863
would cause the camera to jump back to its pre-transform position
after motionpaths were recalculated. This made it seem like a keyframe
wasn't inserted by AutoKeying (even though it was).
Sanity check in node links API: Make sure a valid node exists for both
sockets passed to the nodetree.links.new function, otherwise this could
lead to invalid connections between different node trees! The
ntreeAddLink function has asserts for this, but this condition needs to
be checked in the RNA method calling it.
Interface: avoid setting \0 to drawstr in widget_draw_text
User Interface: add colon separator for number buttons
User Interface: Align number buttons labels to the left, number right
Cache limiter cleanup and small fixes

- Made code a bit less cluttered to follow
- Fixed possible deadlock when enforcing limit
  and highest priority element is still referenced.
Move curve's boundbox and texspace calculation out of modifier stack

There were several issues with how bounding box and texture space
are calculated:

- This was done at the same time as applying modifiers, meaning if
  several objects are sharing the same curve datablock, bounding
  box and texture space will be calculated multiple times.

  Further, allocating bounding box wasn't safe for threading.

- Bounding box and texture space were evaluated after pre-tessellation
  modifiers are applied. This means Curve-level data is actually
  depends on object data, and it's really bad because different
  objects could have different modifiers and this leads to
  conflicts (curve's data depends on object evaluation order)
  and doesn't behave in a predictable way.

  This commit moves bounding box and texture space evaluation from
  modifier stack to own utility functions, just like it's was done
  for meshes.

  This makes curve objects update thread-safe, but gives some
  limitations as well. Namely, with such approach it's not so
  clear how to preserve the same behavior of texture space:
  before this change texture space and bounding box would match
  beveled curve as accurate as possible.

  Old behavior was nice for quick texturing -- in most cases you
  didn't need to modify texture space at all. But texture space
  was depending on render/preview settings which could easily lead
  to situations, when final result would be far different from
  preview one.

  Now we're using CV points coordinates and their radius to approximate
  the bounding box. This doesn't give the same exact texture space,
  but it helps a lot keeping texture space in a nice predictable way.

  We could make approximation smarter in the future, but fir now
  added operator to match texture space to fully tessellated curve
  called "Match Texture Space".

Review link:

  https://codereview.appspot.com/15410043/

Brief description:

  http://wiki.blender.org/index.php/User:Nazg-gul/GSoC-2013/Results#Curve_Texture_Space
Fix for curve pinning raising an exception
UI: Small panel tweak for Dynamic Paint UI, to save some space when color type is NONE
Fix intersect_line_plane bug causing crash on Motion trail and other
similar potential bugs in mathutils_geometry

marking no_flip as TODO
UI: change how number button strings are concatenated (to easy add new suffix)