Syntax highlight for multiple mixins/formatters.

[tempit]

.myClass {
-st-mixin: paramfulMixin('54','200'), paramfulMixin('54','200')
}

2nd mixin param list, strings are not colored as strings.
Scope inspector shows they are not getting string.quoted.single.css and meta.property-value.css scopes.
Check if CSS hardcodes function names, find out how to add our own.

[tempit]

Function names are indeed hardcoded. Need to find out how (and if) it's possible to dynamically color mixins and formatters. Changed title accordingly.