Scanner: Allow single quoted strings literals
This is not a feature for Vala itself, but a feature to allow parse string literals when they are single quoted.
This feature is required by VDA to parse single quoted strings, because that is the way a SQL quotes strings. Parsing SQL statements using libvala's Scanner, is owsome easy, because its tokenized design helps alot.
The required change is not invasive and is simple to use, because requires to add a boolean flag to Scanner and modify a single line of code, no affectations on Vala parsing process in any way.