Removed EUTelMultiLineFit and made some updates to EUTelLineFit

Removing the hopefully obsolete MultiLineFit processor and started fixing the LineFit processor. Still have to find a solution for: https://github.com/tbisanz/eutelescope/blob/86227a77fcd781f08e4025ad40e8720c8e899697/src/EUTelLineFit.cc#L506

Since I don't have any running test example I can't verify the runtime behaviour.

Addressing #5.