minor
fix skipping existing columns in mapping spyne classes to sqlalchemy tables when table already exists.
add non-nullable fk support to o2o relation.
re-implement integer types in order to export _{min,max}_bounds.
transmogrified _gen_col_o2m to generator to allow a Column to be instantiated only after we're positively sure it doesn't already exist.
add experimental AnyHtml type. Currently supported by Xml and Html-based protocols.