BUILD: fix tarball upload directory
mkrelease.sh: use robust HEAD==master check that also handles detached heads
mkrelease.sh: add helper function match() for string pattern matches
mkrelease.sh: use $MKRELEASE_SKIP to skip certain ops for debugging
mkrelease.sh: version increment, history moved to git
mkrelease.sh: remove inherently insecure shellvar command
mkrelease.sh: allow skipping of clean working tree check
mkrelease.sh: parse MKRELEASE_UPLOAD_URL and MKRELEASE_REVISION_VAR from Makefiles
mkrelease.sh: upload tarball before bumping revision
mkrelease.sh: rollback checked out tree after version bump
mkrelease.sh: check versioning before tarball checks
mkrelease.sh: adjust post-release 'master' and 'devel' branches for devel versioning
Merge branch 'mkrelease-updates'

* mkrelease-updates:
  mkrelease.sh: adjust post-release 'master' and 'devel' branches for devel versioning
  mkrelease.sh: check versioning before tarball checks
  mkrelease.sh: rollback checked out tree after version bump
  mkrelease.sh: upload tarball before bumping revision
  mkrelease.sh: parse MKRELEASE_UPLOAD_URL and MKRELEASE_REVISION_VAR from Makefiles
  mkrelease.sh: allow skipping of clean working tree check
  mkrelease.sh: remove inherently insecure shellvar command
  mkrelease.sh: version increment, history moved to git
  mkrelease.sh: use $MKRELEASE_SKIP to skip certain ops for debugging
  mkrelease.sh: add helper function match() for string pattern matches
  mkrelease.sh: use robust HEAD==master check that also handles detached heads