Added support for different table schemas.
Added support for different table schemas.

- Add option for schemaPattern, which allows to select a (set of) table
schema(s) for which to generate files.
- Add option for lower case filenames (and schema folder names).
- Generate files in a separate folder per table schema_name. This breaks
existing includes to previously generated files.
- Namespace includes table schema (namespace::schema_name::table_name).
This breaks existing code using previously generated types.

matthijs/sqlpp11-connector-postgresql,matthijs/sqlpp11-connector-postgresql,matthijs/sqlpp11-connector-postgresql