Include support for .patch files

[dlombardo-fges]

It would great if graphify could support semantic extraction also for .patch files.
I am working on a Yocto build codebase, and most of the layers contain .patch files referring to system built files (like Linux, U-Boot built repositories) that are not included in the graph (otherwise it would be too big and not useful to include also the build).
The patches are essentially representations of what changed w.r.t. to the original file, so it would be useful to include them in the graph to query and ask complex questions.