Support more types in SqliteBack. Improved SqliteBackTests.

Added sqlite backend support for:

* set<int>
* set<string>
* list<int>
* list<string>
* map<int,double>
* map<int,int>
* map<int,string>
* map<string,int>
* map<string,double>
* map<string,string>
Merge branch 'rwcarlsen-sql-types' into develop