Exclude break/lunch times from duration/avg.

[cjwelborn]

Any "in between time" from (configurable) 9-9:15, or 11:30-12, should be subtracted before calculating averages. "Time Before/After" should display a note/symbol to show that a break was taken during that time.

Pseudocode?:

if part_before.end_time <= break_start and part.start_time >= break_end:
    time_between -= break_duration_delta