Tidy Dialect class

- Moved identity/sequence-related methods into "Native identifier generation" region
- Renamed "NH specific" region to "Constraint support"
- Moved constraint-related methods/properties into "Constraint support" region
Merge remote-tracking branch 'ggeurts/NH2959'

Conflicts:
	src/NHibernate.Test/NHibernate.Test.csproj
Review of contributed code (NH-2959)

Whitespace fixes. No functional changes.
Firebird dialect: Add support for returned values from INSERTs (NH-2936)
Ignore NH-2959 test fixture for drivers without multi-query support
NH-2980: Port the enhanced TableGenerator from Hibernate. Make it available under the "enhanced-table" shortname.
NH-2980: Tests for the enhanced TableGenerator.
Nitpick.
Fixed typo - PositionalParameterValues is object[]
Merge pull request #38 from hazzik/patch-1

Fixed typo - PositionalParameterValues is object[]
NH-2964: WhereRestrictionOn().IsInG() is a icollection not ienumerable like it should be
Applied tests for NH-2722 from patch
Implemented NH-2722
NH-2976: Added test case
Failing test for NH-2897
Failing tests for NH-2707
Fix failure to remove item from uninitialized dictionary (NH-2976)

Also, tidies the contributed test and adds a non-generic dictionary version. Support for
the generic and non-generic dictionaries are implemented similarly in PersistentGenericMap
and PersistentMap respectively. And both suffer the same bug.

The solution was inspired by the PersistentList.Remove implementation.
NH-2989 test case and fix
Tests for NH-2722 moved into linq-specified directory
Merge pull request #39 from hazzik/NH-2722

NH-2722: Linq Count() does not respect previous calls to Select() or Distinct()