Multi-file support on wn:resources, enhance model relationships and enable polymorphic relationships

[j-mastr]

Add multi-file support for wn:resources command, with cross links for better resource structure, add static pre-migration relationship check for the existence of all related models, --check-only mode to execute a dry run and simulate resource generation, create migration files in correct dependency order, regardless of the defined order in the resource files

Introduce further parameters to control locations and namespaces of generated Routes and Controllers

Support Lumen polymorphic relationships between models

Minor generation fixes

Could also resolve, but not checked, #38, #43, #52, #59

Not solving, but enabling a dry run option for #27 with the wn:resources command.

Introduces --no-migration parameter on wn:resources, closes #23

Dependency ordering of wn:resources fixes #45

[j-mastr]

(Tests depend on #61)