Update GPX library

[tonymorris]

I am considering updating this library. In particular;

• Use Control.Lens instead of Data.Lens
• Implement zipper
• Implement tests against GPX files
• Implement tests using doctest
• Read whitespace in GPX file so as to recover the original file.
• Rename the package from GPX to gpx (what is the procedure for this?)
• Provide higher-level functions for easy manipulation of gpx files.
• Use Data.Text instead of String
• Use explicit imports and NoImplicitPrelude (code style)
• User a proper coordinate data type

Just wondering if there might be any other interest or comment.

@TomMD

[ocharles]

I would be interested in helping out with some of this, as I have a need to use this package. Specifically, I would be willing to:

• Use Control.Lens
• Use Data.Text

I'm wondering about exposing the constructors more, too. I also think the package would be a lot easier to navigate if there were less modules.

[tonymorris]

Yeah I agree with exposing the constructors where appropriate (i.e. hiding is not to enforce some sort of invariant).

[TomMD]

@tonymorris I appreciate the ping on this, but I don't have the bandwidth to contribute at this time.

Edit: Just noticed the ping was years ago... oh well.