Use new python magic variables api #55
Description
As of recent dev versions, the magic variables in the python console are now defined with an api and don't have to be manually reimplemented. It would be useful if snippets also used this api so you could make use of all the same variables that the console does.
Note: don't actually push this until a stable release comes out, unless you also include a fallback implementation for older versions (like current stable) that don't have this api yet.