Mask modifier: mask by radius

This patch adds the radius masking capability to the mask modifier: everything outside the radius gets masked out.

[jesterKing, 2011-05-25 08:04:52]

I had set the bf-codereview@blender.org wrong, so here a reply to notify that
this patch has been added now.

[brechtvl, 2011-05-25 10:43:09]

I was expecting the option to use an object to specify the center of the mask,
though that probably depends on the use case, I don't know what this modifier is
typically used for.

The radius should be initialized to e.g. 1.0 instead of 0.0, adding an initData
callback in MOD_mask.c and version patch in readfile.c.

http://codereview.appspot.com/4527077/diff/1/source/blender/makesrna/intern/r...
File source/blender/makesrna/intern/rna_modifier.c (right):

http://codereview.appspot.com/4527077/diff/1/source/blender/makesrna/intern/r...
source/blender/makesrna/intern/rna_modifier.c:2134:
RNA_def_property_ui_text(prop, "Radius", "Maskin radius");
Maskin -> Masking

http://codereview.appspot.com/4527077/diff/1/source/blender/modifiers/intern/...
File source/blender/modifiers/intern/MOD_util.c (right):

http://codereview.appspot.com/4527077/diff/1/source/blender/modifiers/intern/...
source/blender/modifiers/intern/MOD_util.c:162: (*texco)[1] =
(*texco)[1]*2.f-1.f;
This extra mapping mode isn't mentioned in the summary, is it intended to be
included in the patch?

In any case, (*texco)[2] should not be left uninitialized.