#177 Several m:n-relations between the same tables causes errors

[Eivind Tagseth]

We have two bi-directional many-to-many relations
between two tables. Middlegen fails to convert the
relation suffixes into Java-names, causing
method names full of dashes and underscores.

Looking at MiddlegenPopulator's
addMany2ManyRelations(), there's an extra

fkRoleSuffix = DbNameConverter.getInstance().columnNameToVa
riableName(fkRoleSuffix);

if there are several relations for two keys(?), but not
otherwise. My case obviously triggered the last.
Adding the same line here fixed my problems.

(this was using 1.54 of MiddlegenPopulator).