Add time property to Waypoints since it's in the GPX1.0 standard.

Waypoints with timestamps are written by my Garmin Etrex 20,
so I want to be able to use them!
Add display of Waypoint time property (only when waypoint has a time).

ATM This field is read only.
Simpler and better use of time display for trackpoints.

This may now show the timezone and no longer have to worry about the newline.
So for example it's easier to see times that were GMT or BST.