Added
- sources can now be given in the reference-point csv files.
- the reference points were redone - there are more of them now and
they are more spaced out.

Added
- references are not longer written by hand but derived from csv-files in the data directory (which should to create them much more easily).
- Some fixpoints would match on the same string. For example in "I am driving 5 km/h." both "5 km" and "5 km/h" would be candidates for adding a reference point. Until now, both reference points would be added (which was confusing). These conflicts are now captured, only the longer string ("5 km/h") is used now.

Added
- numbers and units can now be separated by different types of
whitespace (like tabs) where before only spaces would work.
- the number of whitespace characters separating number and unit
doesn't matter anymore. Before only 0 or 1 was allowed.

Fixed
- False positves where the beginning of a word looks like a unit: `1
mighty sword` had looked like 1 meter and `ighty sword` before. This
would result in the string to be replaced by `1 m (3.33x the length
of a a cucumber)ighty sword`. This doesn't happen anymore'
- Formatting of numbers and whitespace is not changed anymore. Before !
`4,2g` would have been replaced by `4.2 g (...)`.

- can now compare with lengths and masses. Other measurements can be added pretty easily in the source code.
- a 96x96 pixel icon (in addition to the preexisting 48x48 one)

- can now compare with three different reference masses: a chocolate bar, a cat and a lady