A suggestion on making flexipatch-finalizer less final

[Thermatix]

So I don't know if you thought of doing this as a potential method to keep "flexipatch-finalizer" from being so final, but I didn't notice anything like this in the closed issues.

I freely admit I haven't tested this, just wrote this up in GitHub itself whilst trying to keep to the same coding style.
So feel free to "dump on" any mistakes, this is meant as a suggestion or a thought on a possible way to do this (this being, not deleting all the files).

[bakkeby]

Based on the proposed changes I take it that the general idea behind this change is to start a new branch named finalized before finalizing the code?

The flexipatch-finalizer is more final than that given that it deletes the .git directory so branching beforehand would be moot.

Usually you would run the script specifying a different output directory for your finalized build, e.g. something along the lines of:

$ ~/path/to/flexipatch-finalizer.sh -d dwm-flexipatch -o dwm-finalized

In which case the contents of dwm-flexipatch is copied to dwm-finalized before the actual work starts in the latter directory leaving the source directory intact.

[Thermatix]

I forgot about that, I guess setting KEEP_GITFILES=1 should be fine since the branching implies that .git be kept.

I updated the PR to reflect that.