Reviewed proj4js projection definitions.

From what I've learned so far is that proj4js transforms totally fine inbetween
EPSG:3396/7, EPSG:31467/8/9. What spoiled the transformation was a questionable
'towgs84' that I've mistakenly quoted from QGIS. It is left out anywhere else
though, e.g. in http://spatialreference.org/ref/epsg/3397/proj4/ etc.
Transforming back and forth still shifts coordinates by 7mm but I cannot care
less. WGS84 on the other hand is off SW by 184m in QGIS and N by 65m in ArcGis.
What leaves me to the conclusion that neither one of these transforms well to
it and I shouldn't bother calibrating proj4js to either one.
So I'd just transform to plain WGS84 now and adapted the offset correction to
the new projection definitions. It didn't make sense to import data in WGS84 in
the first place, but if it's from EPSG:3397 or EPSG:31469 coordinates more
aligned than before.
Absorbed coordinate offset into function utils/projector.

(EXPLAIN ME NEXT WEEK!!!)