* Use `rev-parse` instead of `show-ref`
* Dev builds currently use masters commit ref and makes it difficult to determine which version is really installed with About → Help. Use the current HEAD when generating the `Makefile`s for `DGIT_REVISION`
**NOTES**
* The bash scripts are somewhat duplicated with the unused `--short` parameter but omitted at this time in case a long hash is wanted.
* `make distclean` is still needed since those defines are hard-coded into those affected `Makefile`s
* Keep current abstract as per @nowrep
* Remove some known unneeded bash pipes