Be more strict on Tryton module names.
Raise an error if the Tryton module name passed to 'get_prefix_require_version()' contains a dash.
I was trapped by different notation of a Tryton module name between tryton.cfg (underscore) and setup.py (dash) which let to the module to be added to the dependencies twice: Once with prefix 'trytond' from tryton.cfg and once with the (desired) custom prefix from setup.py. The new error will catch these cases.