Issue #26
- Overlay tool now displays normalized curves
- supplementary parameters may be used for plot normliazation
- bugfix and performance tweak: importing data with PageInfo tool opened.
- increased accuracy in session saving (20 digits - ridiculous)
- changed the possibility to save comma- and tab-separated values in csv
- PyCorrFit now saves .csv files as tab-delimited files
  --> this makes it easier to import data into Excel-like software
- kosmetik: when name of background too large -- crop in page dropdown
- background now calls OnAmplitudeCheck of each page if bg data is imported
- minor fixes