Update src/T4/OrmLite.Core.ttinclude

The following changes where made:
- changed ProperPropertyType to use CheckNullable function
- changed function CheckNullable to static
- changed function LoadTables to accept makeSingular param
  if makeSingular is false ClassName = CleanName so ignores Inflector.MakeSingular
- changed function GetPK to return "" if primary key colums is multiple columns
Update src/T4/OrmLite.Poco.tt

Added 3 new options:
- MakeSingular, default true. if true: Changes the classname to singular if tablename is not singular
- UseIdAsPk, default true. if true: Changes the primary key property name to Id
- GenerateConstructor, default false. if true: Generates the default empty constructor
Merge pull request #182 from WimAtIHomer/patch-1

Added 3 new options to OrmLite.Poco.tt