--new-pr should be able to handle patch files

[verdurin]

When I was trying to use --new-pr to update SAMtools, I needed to include an updated Makefile patch.

--new-pr thought that the patch file I included was an easyconfig, so it complained about the lack of an easyblock specification.

I suppose this implies the need for a new option to indicate which files are patches.

[boegel]

@verdurin I included a pointer to this in #1674

We can probably detect whether something is a patch file, but the hard bit is to figure out where the patch files should be located...
Maybe we need to look through the patches values in the easyconfig files being included, and figure out where the patch belongs.

[boegel]

work-in-progress PR for this: #1751

[boegel]

fixed in #1751