Add "forceDelete" flag

[Knetic]

While forcing the generation of a project is already possible, it is sometimes desirable to delete any existing files at the output location before creating a new project. Currently this is not supported; forcing generation overwrites contents where they conflict. Both features should be possible.

A -d flag should be added that, when the -f flag is also specified, causes the output directory to be completely removed before project generation. Otherwise the -f flag should purely cause overwrite, as it does today.

[Knetic]

Done as of cd50de4