feat(src): add clock edit mode

Adds modes for the clock app, that may be
changed. The new mode added is clock edit mode,
that adds support for editing the current clock.

feat(src): turn off autobrightness adjustment after manual adjustment

chore(src): format with cargo-fmt

feat(src): add meaningful message to panic in Calendar::days_in_month

feat(src): add calendar freezing possibility

feat(src): add setter methods for Calendar

Allows to change the current date of
already existing calendar.

feat(src): implement Calendar::from_ticks for arbitrary year, add Calendar::to_ticks

So far, Calendar::from_ticks could not correctly parse
other month than the base month, this commit fixes that.

Calendar::to_ticks may convert any Calendar date to seconds passed from
the base year. The base year is remembered in Calendar instance.

chore(src): move source to source/ folder

feat(src): add app state with calendar