Add more files to ignore, when building on Windows
[QA] Actually use results from IS_VIK_* calls.

Spotted via compiling with Clang.
[QA] Reduce warnings when compiling with Clang.

Don't need to:
Comparison of unsigned expression >= 0 is always true [-Wtautological-compare]
+
Explicitly assigning a variable of type to itself [-Wself-assign]
Maintain script output of TrackWaypoint layer format.
[QA] Better variable naming
[QA] Remove unneeded include.
Add map layer option to only download missing tiles.

Useful for low bandwidth and/or pay for data services yet you want the convenience of the autodownload.
Also useful for map types which hardly ever change e.g. BlueMarble,
 so no need to bother the server to ask if there are newer tiles!
Rework TrackWaypoint layer option to draw 'All Tracks Black' into 'All Tracks Same Color'.

Thus in this track drawing mode you can now specify the colour used, instead of only being black.
For compatibility the default is black.
Ensure when creating tracks they are allocated a colour.
Add file version to .vik files.