Removed most of the bare Exception catches and put proper errors to catch in their place.
Reworked a bit of the gridsquare calculation, any exceptions raised should now be handled within the function.
I am purposefully leaving the 2 W0703's we have for data demodulation alone for now, as that will be quite a rabbit hole. Otherwise,
fixes#316
Signed-off-by: Corey Shields <cshields@gmail.com>