first draft at a helmert transformation
* converts from polar to cartesian based on Airy 1830
* converts from cartesian to polar based on Airy 1830
* need to handle different ellipsoids
* trasform polar to cartesian co-ords
* transform caresian to polar co-ords
* clean up code of helmert a lot
* by combining output can transform between datums
* -1 error with height
* next step is to move these php functuons to C functions and create convert datum PHP function and wrappers
* apparently - height is correct
* better set up of constants
* more tests
* move constants into structure and allow reverse helmert
add 2 new functions to convert co-ord formats
clean up names and prototypes
* spaces to tabs
* more comments
* fix spacing in copyright notice
* add test for decimal minutes
* add test on prime meridian based on this photo http://upload.wikimedia.org/wikipedia/commons/a/a1/Garmin_GPS_at_Greenwich_Observatory.jpg
Merge pull request #3 from natmchugh/helmert_transformation

Helmert transformation