Use hit property field to distinguish between fitted and measured hits

This PR addresses issue eutelescope/eutelescope#11 and includes some cosmetic changes (indentation and removal of commented-out code fragments).

The only remaining code which still uses the type field is in:
- [ ] EUTelAPIXHistograms.cc
- [ ] EUTelAPIXKalman.cc
- [ ] EUTelMultiLineFit.cc

I had the impression that these processor might be obsolete -- does anyone know their status?
EUTelAPIXKalman also does not yet set the sensor ID of fitted hits (see eutelescope/eutelescope#40).