Added facilities for running scripts. Templates.

- Implemented facilities for running scripts.
- The interpreter and compiler can be changed on-the-fly.
- Added maps and menu entries to set the output redirection.
- Bugfixes.
- Reworked the template library.
- Added and corrected codesnippets.
- Documentation.

taken from WolfgangMehner/vim-plugins, revision
https://github.com/WolfgangMehner/vim-plugins/commit/4ee8ee8216a0d603a1f5b24d920d72a90d297829