Allow easy inclusion of sample inputs in gen/GEN
Fix and streamline GEN file loading in YamlImporter and cmsMake.

Also, implement correct dependency tracking for #COPY: statements.
Use more descriptive names for variables.
Clarified that checker is executed on the workers

When the computer where the task is prepared has a different
architecture than the workers, it is possible that the resulting
checker does not run correctly on the workers. Thanks to Gabriele for
the spotting this.
Reming to compile the checker statically in the task type page