Fixing support for Pebble Time Round

Trying to implement Timeline Preview support for Pebble Time Round and fix weather icon displaying.

Modified version of 15.7.0

Changes in this release relative to the original version:

1. Added support for Unobstructed Area API. This means that when timeline preview pane is shown, watchface will shift to avoid timeline hiding current time. (Not for Pebble Time Round yet!)
2. Slightly changed time format for sunrise/sunset displaying. Now in AM/PM mode leading zero will be omitted, and A/P will be added to denote AM or PM correspondingly. If hours is two-digit then AM/PM will not be displayed as it can probably be easily guessed.

This mod was requested and sponsored by Brent, thanks!