Remove module class LAMDAQuery for functional form

The class `LAMDAQuery` was unnecessary since not messages were being
sent from other classes and no attributes were being changed by the
user. The methods in the class have been moved to be simple functions in
the sub-module `lamda.core`. Some code-cleanup, de-linting, and pep8 has
also been done.
Update tests for new style

Also added test for printing molecule list and made the collisional rate
test more complicated.