Removed some errors¨ in bl_to_xy by comparing to original holsen

Changed some inconsistencies between holsenjs and holsen. It seems like holsen have an error on about 5 cm on the north values. Have therefore added tests that both compares with holsen and with values
from norgeskart.no.
Some testing revealed that coordinates outside of Norway or far east in Norway caused some issues. But at large areas of Norway the results got very good. I can say more later. Don't have time right now