enable split-time activation modes - continuous, manual, auto, accumulated

[tshalif]

split time measuring should have the following modes:

1. continueous
   ROWING_START event is fired as soon as entering this mode, ROWING_STOP is never fired. Long press on time meter will reset avg/count split time/distance meters
2. auto
   with auto start constraints (if checkboxes are selected) of either:
   • single activation (press on time meter for single-activation of auto-start)
3. manual
   start/stop manually

In addition, there are the following non-mode options:

• reset meters on start
  zero meters when starting - either manually or automatically

manual zero/reset by long press should also be possible at any time