Gui Improvements

[pateltanmayp]

A set of small improvements to the GUI:

1. The path is now displayed with its actual width (referenced to the underlying map, not the screen). It adjusts dynamically as you zoom such that the path annotation remains true to the map for all zoom levels.
2. The path width is now shown as a translucent band, with a black centre-line along the actual path.
3. A toggle now allows you to select the whole path at once without needing manual selection.
4. If the /novatel/fix topic is present (the topic is configurable), the path is automatically initialized at the location of the first GPS coordinate. The initial heading is approximated using the first few GPS points but this is not fool-proof. Manual rotation may still be required (improvements to follow in a future PR).
5. When the selector is used for annotating or merging, it is now set to point 0 of the path, instead of the point along the path closest to the centre of the map.

[a-krawciw]

I haven't yet had the chance to run the code myself. A few minor improvements but overalll looks really good.

[a-krawciw]

A couple of minor comments

• The Annotate Route button has no effect once this mode is selected
• There is a bit of a horizontal gap to the Annotate Route button

Some warnings you can clean up if you are feeling extra thorough!

[pateltanmayp]

A couple of minor comments

* The Annotate Route button has no effect once this mode is selected

* There is a bit of a horizontal gap to the Annotate Route button

Some warnings you can clean up if you are feeling extra thorough!

All should be addressed.