Update XML Namespace URI for KML

The XML Namespace http://earth.google.com/kml/2.2 returns a 404,
as do other similar Google URIs for KML 2.2.  This causes the output
not to validate.  Changed to http://www.opengis.net/kml/2.2
Add GPX support

Supports conversion to GPX.  Each timestamped point is included,
and they are grouped into individual tracks, with a split between
every two chronologically-adjacent points that are more than 10
minutes or 40 kilometers apart.  It appears that GPX waypoints
may not have timestamps, thus the decision to make tracks.

Some useful resources:
*
http://stackoverflow.com/questions/27928/how-do-i-calculate-distance-bet
ween-two-latitude-longitude-points
* https://gist.github.com/bluemaex/4235529
* http://cycleseven.org/gps-waypoints-routes-and-tracks-the-difference

Updated README and tested on a very large Latitude JSON history file.
Merge pull request #1 from kjkjava/fix-kml-xmlns

Update XML Namespace URI for KML
Merge branch 'master' into add-gpx-support
Add KML details

I added extended data to points when available (including accuracy,
speed, and altitude).  The TimeStamp tag could be included in
ExtendedData to make an online KML validator happy, but then
Google Earth doesn't utilize it as time data.
This seems to be the best solution.
Make KML 2.2 valid

I learned that order of elements does matter, so after
rearraning the order of things, the KML output is valid
and works well in Google Earth.
Add GPX details when available and ensure valid GPX 1.1

Included altitude, speed, and accuracy data in the
conversion, when available.  Also, ensured the output
validates as GPX 1.1.  This requires the elements appear
in the order they are in.
Update README

Minor cosmetic updates and details regarding changes to the KML output.
Update README to better detail the GPX format
Distinguish between gpx and gpxtracks format

Added the option to save in GPX format without grouping points
into tracks (like all other current formats).  Originally, I thought
tracks
were required to include time data, but I must have misformatted the
data.  Now, both options are available as "gpx" and "gpxtracks" and
both validate.
Merge pull request #2 from kjkjava/update-kml-valid

Add KML details and ensure valid KML 2.2
Merge pull request #3 from kjkjava/add-gpx-support

Add GPX Support
Add contributors