* Added an optional array of MDeformModifier pointers, to avoid another search based on defgrp_idx.
* Split out "add/remove verts from vgroup" functions, preparing their move to deform.c (if their current form is validated!).
- use 'const float *' and array size in some function declarations.
- replace macros for BLI_math functions INPF, VECCOPY, VECADD etc.
- remove unused VertRen.clip struct member.
- remove static squared_dist() from 2 files, replace with BLI_math function len_squared_v3v3().
- use vertex arrays for drawing clipping background in the 3D viewport.
*Updated UI code (replaced “row columns” by splits ;) ).
*Clamped global influence to [0.0, 1.0] range!
*Added/edited some tooltips for Proximity.
*Proximity distance mapping can now be reversed by entering Lowest Dist > Highest Dist.
*Moved mapping before masking in Proximity, much more sensible this way!
*Added Smooth/Sharp/Root/etc. mappings to WeightVGEdit modifier, in addition to custom curve one.
*Added Smooth/Sharp/Root/etc. mappings to WeightVGProximity modifier, without the custom curve one!
*Factorized the common mapping code into MOD_weightvg_util.
- was doing NULL checks on freeing memory in cases where the values were already accessed (blender would have crashed anyway), so remove the NULL checks.
- use deform.c api weight functions to replace inline weight lookups in some cases.
- change if checks in weightvg_do_mask() so its more obvious whats going on.
*Removed curve init code in readfile (no more needed since the split broke anyway compatibility with earlier WeightVGroup files…).
*Updated get_ob2ob_distance() code (much simpler – I’m not a matrices’ god!).
*Enhanced a few RNA names (Campbell has others in mind here, though, I think).
