[Bf-committers] Modal bevel operator (issue 6208066)

[kalast at gmail.com]

Reviewers: bf-committers_blender.org,

Description:
This patch modifies the bevel operator slightly so that it becomes
modal. Moving the mouse will modify the bevel factor and E/D keys will
change the behavior of the tool

Please review this at http://codereview.appspot.com/6208066/

Affected files:
   source/blender/editors/include/ED_transform.h
   source/blender/editors/mesh/editmesh_tools.c
   source/blender/editors/mesh/mesh_ops.c
   source/blender/editors/space_view3d/view3d_edit.c
   source/blender/editors/transform/transform.c