GPS coordinate parsing

[Dirk Hohndel]

I just pushed a commit that attempts to improve the parsing of GPS
coordinates:

    We used to only support full degrees and decimal minutes. We now also
    support fully decimal and degrees, minutes and decimal seconds.

    The previous implementation only accepted a decimal point. We now support 
    both point and comma, regardless of locale.

    The previous implementation would color the input field red if either it
    couldn't parse the string, or if it was able to parse it but it was the
    same as the previous location. That's misleading.
    
    The previous implementation also changed all gps coordinates to the new
    coordinates in a multi-dive edit - instead of just changing the ones that
    are the same as the master dive.

Since I am hoping to release 4.0.1 before the end of the year I would
really appreciate if people could beat on this change a bit. Try the
multi dive edit to make sure it makes sense (basically, if several dives
are at the same location, then changing the gps coordinates should be
tracked in all of them - but if they have different locations, then this
should only affect the selected dive). And please test the parsing of
the different GPS formats. Supported are

N7° 16.29924' , E134° 14.74350'
N7° 16' 17" , E134° 14' 44"
7.271654 , 134.245725

I'm sure there are a few bugs still hidden in there somewhere. And I'd
like to catch them before we release this on our users :-)

Thanks

/D