Fix T42966: Py_Initialize: Unable to get the locale encoding

This only happened for SCons builds and caused by pure human stupidnes.
Quick fix for UI themes, by meta-androcto (Brendon Murphy), thanks.
partial revert ab6417aa9ff8cbd4831c3ed1837742c1178be25a was too strict
Fix T42952: Curve modifier not taken into account when curve is created from mesh

Curve and array modifiers requires curve path to be evaluated, dependency graph
will make sure that curve eval would create such a path, but if curve was already
evaluated we might miss path.

So what we do now is: if path was not calculated for target curve we tag it for
update.
Fix T42928: Drag-drop of generated files to compo reloads them, loosing edits

Origins of this issue goes back to T33402, where compo wasn't sure what kind
of image it is working with (compo should know if it's multilayer or regular
image).

Now we only reload images when dar-dropping from outside of blender.
Add missing keymap for paint curve
Fix T42994: Own recent regression in fix for T42945 (rB5cc199e49581),
side/front/top ortho views would no more adapt their snapping unit to zoom factor.

This code would need slightly more refactor actually, but this will be for after release!
Blender 2.73 release candidate commit

This commit contains:

- Subversion bump to 2.73
- Release cycle is set to "rc"
- Submodules are pointed to appropriate tag now
  (addons contrib just points to the latest contrib repo)
- New shiny splash screen!
Merge branch 'master' into sticky_keys