Big relevance overhaul, prompted by #325:

- zeroed relevance of 'anything followed by :' in autohotkey, coffescript, smalltalk
- special relevance counter for brainfuck, consisting only of ++ and --
- dropped most `relevance: 0` from haml, as those modes are pretty strictly defined, dropped `relevance: 10` from the '%' character instead
- added 'require' to javascript built-ins
- defined `'use strict'` as a processing instruction in javascript
- illegalized ':' within `{ .. }` in matlab and mathematica
- zeroed relevance of `[ .. ]` and variables in matlab and scilab
- redefined smalltak localvars to include every var inside the expression into relevance count
- zeroed relevance of vbscript '-comments
Setting relevance of all common-looking strings to 1.

It doesn't affect relative relevance of languages that do use
common-looking strings but helps them to distinguish themselves
against languages that use '-comments or something like this.
The latter languages had an unfair advantage until this point.
Add JavaScript .pi to classref
Merge branch 'relevance'.

- Reworked relevance for a few languages.
- Relevance for all common-looking strings brought to 1.
- JavaScript's got 'pi' definition.