refactored constants and enums

- replaced FCOEV2_mode_status_enum by an equivalent set of #define 

- replaced CAMERA_OFF and CAMERA_ON values by int values instead of
boolean

- added CAMERA_RUNNING and CAMERA_IDLE defines for running/idle status
Externalized delays to observe after calling switchOn and
switchToNextMode

- the delays are no longer automatically done (except for switchToMode),
but must be done explicitly after the application calls to switchOn and
switchToNextMode