Don't prefix tag names with 'v'. If you want that behaviour, include the 'v' on the command line manually.

Dynamically collect the true git exec path and only if that can not be found, use the default. Variable GIT_EXEC_PATH remains overwritable explicitly when given as a command to 'make'.

Conflicts:
	gitflow

- now works as sub commands to git if copied to $(git --exec-path)
- now works with arbitrary commands for branch types
- consistent variable names
- new branch type 'support' for long-term support branches of historic
  versions
- preliminary base branch support for hotfix branch type to create
  hotfixes form support branches

Don't do --no-ff merges for feature branches that exist of a single commit (no benefits are gained in those situations, only complexity is added).