Make app compatible with Bangle.js 2:
- check hardware
- _drawString(s, x, y)_: removed _x_, always centered
- _drawString(s, y)_: _g.reset()_ before _g.clearRect(...)_
- adjust heights for Bangle.js 2 for each _drawString(s, y)_ call
- _drawApp()_: on Bangle.js 2's always on display save energy by drawing time only at every next minute
- _drawTime()_: hide seconds on Bangle.js 2 (only refreshed every minute)
- _drawApp()_: add _"Alarm at "_ to distinct from actual time (no difference in seconds)
- execute _load()_ on Bangle.js 2's BTN