quilt is a collection of bash scripts to manage a series of patches by
keeping track of the changes each patch makes. Patches can be applied,
un-applied, refreshed, etc.
The key philosophical concept is that your primary output is
patches. Not ".c" files, not ".h" files. But patches. So patches are
the first-class object here.
Quilt was originally based on Andrew Morton's patch scripts published
on the Linux kernel mailing list.