Outline math - Complete rewrite

The outline math plugin (votl_math) has been rewritten to:
1. handle integer, floating-point and scientific notation
2. handle multiple passed variable per heading
3. calculate multiple formulae per heading

Mappings:
<localleader>mm    quickly compute this heading and up (ancestors)
    to recalcuate for a quick edit to this heading
<localleader>mt     compute this heading and all the child leaves and branches
    to recalculate for this heading and any child/offspring modifications
<localleader>md    compute the entire document
   to recalculate everything