Added support for new Pebble Time 2 along with many features

[bentemple]

Sorry, kind of an insane PR and no real pressure to merge this, but wanted to make you aware of my fork and offer to merge them upstream if you'd like. Hopefully the pebble core 2 duo will be largely un-impacted by these changes besides the new features like uptime and new progress bar %s (I have tested it, but not as thoroughly as on the Pebble Time 2)

• Progress bar can show % of sleep and step goal
• Added concept of UpTime (Time awake since last night sleep)
• Added unit tests to validate uptime logic
• Split apart main.c into sub components
• Lots of pedantic caching to reduce any potential battery drain from unnecessary redraws of the screen or calculations
• Added today/tomorrow high temperature after current temperature. (Tomorrow's high is shown after the current day's sunset)
• Fixed fonts on Pebble Time 2 screen
• Lots of color support for the pebble time 2, dynamic progress bar coloring, accent coloring, weather coloring all configurable via clay
• Added low battery indicator when < 10% battery
• Show actual battery % while charging in progress bar

[bentemple]

PS: Thanks for making one of my favorite watch-faces, for making it open source, AND for using Clay. you rock.