[Therion] declination

[Wolfgang Zillig]

Hi,

I've just changed one input file from survex format to therion format to 
get the LRUD data into the model. The declination is corrected manually 
by "declination xx degree" within the centreline. I've noticed that I 
had to change the prefix from "-" (minus) to "+" to get the same result 
as with survex. In survex it is done by "*calibrate declination xx".

It would be nice to add a comment in the Therion book that declination 
correction is opposite from Survex.

Regards
Wolfgang