Adding gsub function
Adding gsub function
Adding capture group test case
Merging remote
Merge upstream into adding_gsub_function
Adding replace function

* renamed gsub function to replace
* reordered replace's function arguments to be much more readable
* added support for replacement (Regexp) options
Replacing replace's options to flags
detached rulesets
Merge remote-tracking branch 'origin/master' into detached-rulesets
more tests and name arguments for caller
small simplification
do not chunk inside parens so that we can predict mixin calls containing detached rulesets. Also now save the current chunk (may not be required).
add some more failing tests
implement n level back-tracking and then don't absorb a parenthesis, fixing both issues with 2 new test cases
Test out some theoretical back tracking and fix bugs
small approx 1% speed improvement
Merge remote-tracking branch 'origin/master' into detached-rulesets
add scope tests to the detached ruleset test-set
error tests and test detached rulesets without a mixin call
Fix one issue with media queries and detached rulesets, one to go