A Rework plugin to support calc().
Particularly useful with the rework-vars
npm install rework-calcAs a Rework plugin:
var rework = require('rework');
var calc = require('rework-calc');
var css = rework(cssString).use(calc).toString();This simply add calc() support, a feature to do simple calculations.  This
can be particularly useful with the rework-vars plugin.
Note: When multiple units are mixed together in the same expression, the
calc() statement is left as is, to fallback to the CSS3 calc feature.
Example (with rework-vars enabled as well):
:root {
  --main-font-size: 16px;
}
body {
  font-size: var(--main-font-size);
}
h1 {
  font-size: calc(var(--main-font-size) * 2);
  height: calc(100px - 2em);
}yields:
body {
  font-size: 16px
}
h1 {
  font-size: 32px;
  height: calc(100px - 2em)
}See unit tests for another example.
Make sure the dev-dependencies are installed, and then run:
npm testMIT
