Fix for BMesh Bevel Operator

This patch fixes issues with the current bevel operator.
1. Correct absolute distance bevelling. The user can now specify an absolute distance which all edges will then be offset. This doesn't work in the trunk bevel op.
2. Better defaults. Now by default it is set up to do absolute distance bevel.
3. Consistency. Options are now named in the same fashion as the inset operator for consistency between tools. The options also have the same effects as other tools.

[ideasman42, 2012-04-05 09:58:18]

Added some comments & requests for clarification.

http://codereview.appspot.com/5967069/diff/1/source/blender/bmesh/operators/b...
File source/blender/bmesh/operators/bmo_bevel.c (right):

http://codereview.appspot.com/5967069/diff/1/source/blender/bmesh/operators/b...
source/blender/bmesh/operators/bmo_bevel.c:265: #if 0
would be nice to give some brief description as to why this is disabled. what
issues did it cause? - or if its real useless, just remove.

http://codereview.appspot.com/5967069/diff/1/source/blender/bmesh/operators/b...
source/blender/bmesh/operators/bmo_bevel.c:331: mul_v3_fl(co, 1.0f /
sinf(angle));
can't shell_angle_to_dist be used here?

http://codereview.appspot.com/5967069/diff/1/source/blender/bmesh/operators/b...
source/blender/bmesh/operators/bmo_bevel.c:367: mul_v3_fl(co, 1.0f /
sinf(angle));
again? - shell_angle_to_dist

http://codereview.appspot.com/5967069/diff/1/source/blender/bmesh/operators/b...
source/blender/bmesh/operators/bmo_bevel.c:402: BM_ITER(l2, &liter2, bm,
BM_LOOPS_OF_VERT, l->v) {
I don't follow the logic here, might it be better to test BM_EDGES_OF_VERT ?

http://codereview.appspot.com/5967069/diff/1/source/blender/bmesh/operators/b...
source/blender/bmesh/operators/bmo_bevel.c:415: angle = angle_v3v3(co_other,
co);
again - shell_angle_to_dist?

http://codereview.appspot.com/5967069/diff/1/source/blender/bmesh/operators/b...
source/blender/bmesh/operators/bmo_bevel.c:420: mul_v3_fl(co, 1.0f /
sinf(angle));
again - shell_angle_to_dist?