Utils: Rename Daemon::fail() to Daemon::exit()

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

Utils: Implement ErrnoException

Make all include path's relative
Add 'senf/Packets.hh', 'senf/PPI.hh' and 'senf/Socket.hh'

Socket/Protocols/INet: Add INet4Address documentation
Fix some missed INet4Address -> INet4SocketAddress renames
Fixed several std:string arguments to use std::string const &

* Allow empty FileHandle/SocketHandle etc instances
* Make ServerSocketHandle::listen depend on AddressingPolicy
* Replace all occurences of inet_ntoa with inet_ntop (thread safety)
* Fix handling of exceptions in ReadHelper/WriteHelper
* Fix Scheduler ERR/HUP semantics

Unified emacs Local Variables

Renaned directory satscons to senfscons

fix EPOLLERR and EPOLLHUP handling