Organized type handlers and tests

No actual work
Work on LastInsertedOID

Moved from command to the reader, like RowsAffected, and made to work.
More fixes around reader/command

* Fixed empty query scenario
* Removed incorrect invariant and requires contracts
Work on network types

* Aliased CIDR to INET
* Implemented binary encoding for INET/CIDR and MACADDR
Fixes to geometric types

* Added invariant culture for all String.Format() operations, thanks @Emill
* Two other small fixes
Added missing Ensures in sequential row