Added property map for constant values

Added ConstantPropertyMap to support mapping to constant values, such as with Table-Per-Hierarchy (TPH) polymorphic entities.
Multiple mapping fragments,better schema detection

Adds support for multiple mapping fragments
Improves schema name detection
Add BulkInsert and InsertFrom
Update Source/EntityFramework.Extended/Extensions/BatchExtensions.cs
Add BulkInsert, InsertFrom
Add BulkInsert and InsertFrom
Add DB Type Conversions
Add inner Select builder
Added new dynamic operations
Merge branch 'master' of https://github.com/wolffit/EntityFramework.Extended

Conflicts:
	Source/EntityFramework.Extended/Dynamic/DynamicQueryable.cs