Use vagrant-cachier to use system's cache for packages if possible
fix cps whitelist, simplify two parameter definitions
leave a hint how to draw outlines instead of filled
repair List operator
repair negate operator
Merge pull request #246 from graphicore/fixes-for-formulae-language

Fixes for formulae language
Add operators to perform calculations using the math/hobby module.
Allow names to begin like existing non-splitting tokens.

e.g: `Skew` is an operator and `SkewTransform` is an allowed name.
Parse 'Infinity' as a number
Allow negative indexes in :i pseudo class selector.
Fixes for details of the hobby module.

* normalize angles
* return a tension of Infinity when a magnitude is 0
* fix behavior of the tension2control functions when tensions are undefined
* ensure _magnitude2tension returns Infinity when magnitudes are 0
show only branch master in travis build status image
Merge pull request #243 from graphicore/bugfixes-hobby

Fixes for details of the hobby module.
Merge pull request #244 from graphicore/fixes-for-Vector

fix cps whitelist, simplify two parameter definitions
Merge pull request #245 from graphicore/hint-for-drawing-outlines

leave a hint how to draw outlines instead of filled
Merge pull request #247 from graphicore/improvements-for-formulae-language-and-selectors

Improvements to formulae language and selectors
Fix rembering of 'lastVector' in MOMPointPen
fix reading of skeleton on-curve point, formatting
fix: make jshint pass
remove outdated detail