FSharpComposableQuery.Tests:
 - Removed old code testing performance of F# 2.0 query builder in People.fs
 - Added ExtraTests.fs with specialised query tests
FSharpComposableQuery
 - Changed the signature of Exp.Source in order to replace it more easily inside different types of queries
 - Added (currently inactive) code to substitute the type of Source calls inside different types of queries
 - Added back the runQuery method