- renamed "description()" member to "errorString()", 
   - renamed "where" attribute to "description", 
   - changed "what()" ouptut.

Changed all exceptions to inherit from senf::Exception
Replaced all throwErrno() calls with throw SystemException()

PPI: Allow access to source/sink helper in (Active|Passive)Socket(Source|Sink)

Replace all 'throw SystemException(...)' commands with 'throwErrno(...)'
Add additional links to documentation header

Utils: Implement ErrnoException

Unified emacs Local Variables

Renaned directory satscons to senfscons

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