[Therion] Turn through angle data format

[Andrew Atkinson]

May I add this to the wish list.

every few years I get data in a land survey format, which often does not
use a magnetic survey but a turned through angle (does it have a proper
name?) I guess it is not that easy, otherwise this sort of think usually
gets done.
Readings from two stations look something like this.

                                    OBSERVATIONS
                                    ------------
LOCATION     : Wookey                                       JOB NO  : 164
DATE SURVEYED: 19 MAY 2015 16:                                FILE  :
TI16401
SURVEYOR     : D                       Factors:          EDITED
STN          : 1   H.I.  1.410


 PNT   HA       VA       SDIST    TGT    CODE        DIMS         REMARKS

   1   0.0000  90.1539  59.621   1.510 SS00000N  ~                #SS 2#
   2 217.5531  73.4609  16.824   1.655 SS00000N  ~                #SS 3#
   3 359.5958  90.1545  59.621   1.510 SS00000N  ~                #SS 2#
   4 217.5524  73.4617  16.825   1.655 SL00000A  ~                ~
   5 359.5959  90.1538  59.621   1.510 SS00000N  ~                #SS 2#

                                    OBSERVATIONS
                                    ------------
LOCATION     : Wookey                                       JOB NO  : 164
DATE SURVEYED: 26 MAY 2015 20:                                FILE  :
TI16403
SURVEYOR     : D                       Factors:          EDITED
STN          : 2   H.I.  1.420


 PNT   HA       VA       SDIST    TGT    CODE        DIMS         REMARKS

  12   0.0000  94.1903  14.233   1.400 SS00000N  ~                #SS 2A#
  13 355.2701  89.3842  59.615   1.420 SS00000N  ~                #SS 1#
  14   0.0004  94.1754  14.233   1.420 SS00000N  ~                #SS 2A#

I think this is how they come out of the machine, but cannot be certain.

So the first set of observations are all from station 1 (well
technically 1.410 above station) so the first line of that set is a
reading to ss 2 or station 2, which has been set at 0 and ss 3 is 217
degrees from that reading (No relation to North.)

Obviously this type of data cannot be used without 2 statoins of know
possition somewhere on the traverse. We have 2 ends of magnetic survey
to connect this survey too.

Anyway it would be great to get this data into therion/survex, the
tunnellers of Wookey really need it, 15m in and they are not sure what
direction to go.....

Slight formating problem that might also be nice to solve, although it
is messy, and not to be encouraged is that 217.5531 means 217 degrees,
55 munites 31 seconds

thanks

Andrew