New scm lib/plugin with combined new theme

I started a new lib scm (on top of the git) to open the support for multiple scm systems (git, hg, svn). The commits include:

+ added bash functions to termsupport for xterm-256 supporting 256 coloring
+ new SCM lib/plugin
  - caching of prompt-info
  - SCM root detection (git, hg, svn)
  - initial support for multiple SCM prompt infos
+ new 'pixelplastic' theme showing capabilities of new SCM lib/plugin

Still missing:

+ Support for hg and svn SCMs
+ sometimes the prompt-info caching does not refresh appropriate

So this PR should be open for discussion.