Refs #9445. PoldiPeakCollection now holds peak intensity type

A PoldiPeakCollection now stores information about the type of intensity
information assigned to the contained peaks. Some parts need to work
with the peak maxima, others need the area. This information is now put
into the workspace logs and processed.
Refs #9445. PoldiCalculateSpectrum2D processes POLDI peaks

Instead of the fixed example peak, a peak table is now loaded and the
corresponding functions are constructed.