Added test for Posgresql Array parameters

Added test for insert updating object's key

Update object's key(s) after insert and array parameter support.

Added FeatureSupport Class to handle variations int DBMS features, used this to implement native array parameters for Postgresql.

Small but useful (I think) additions

Added postresql support for Insert to return primary key of inserted row.

Conflicts:
	Dapper.Contrib/SqlMapperExtensions.cs

Broke SqlBuilder to another assembly
Added Dapper.Rainbow (minimal ORM)
Changed nuget to distribute DLLs

allow Add to *replace* an existing template parameter in DynamicParameters, allowing for out/return/etc usage

fix 'could destabilise runtime' error if structs threw an error; also tidied up the locals and made the func return the right type