Changed TType to TEntity for consistency
Added foreignKeyFinder to support foreign key mapping
Optimized ForeignKeyInitializer by idFinder and fkFinder which can cache property search result.
Updated FakeDb.Db to support foreign key mapping.
Added foreign key mapping related unit tests.
Converted ForeignKeyInitializer into fluent api
Merge branch 'master' of https://github.com/buddhike/FakeDb
Merge branch 'ft-foreignkey-mapping'

Conflicts:
	src/FakeDb/Db.cs