Implemented the following methods:
* SIMCURHAND_TYPE
* SIMCURHAND_RADIUS
* SIMCURHAND_WEIGHT
* SIMCURHAND_DIRECTION
Limits:
* DIRECTION does not support surfaces, because `BKE_nurb_bpoint_calc_normal`
does not work with Nurbs of type `CU_CARDINAL`. This also didn't work prior
to this patch, so we wait until surfaces are properly supported in EditMode.
* Also DIRECTION should take scaling into consideration. We need our own
versions of BKE_nurb_bpoint_calc_normal/bezt.
* Threshold default is too large. Not sure if it's better to change the default
or scale the threshold in code.
Differential Revision: https://developer.blender.org/D3846
Changes from committer (Dalai Felinto):
* Moved nurb_bpoint_direction_worldspace_get/bezt to functions.
* Comments hinting at the mode (direction) that require scaling to be
taken into account - to be addressed by patch creator in a future
patch.
Add tool options to control how select operates (add/sub/set/and/xor).
Note: edit mode armature select still needs to support all options,
this is complicated by how it handles partial end-point selection.
