start config.h file

Compile-time configuration with a seperate header will allow some
end-user firmware customization in a clear location.
start work on long button presses

Long button presses are expected for future features, like strobe.
use TICKS() macro

There is no need for TICKS_PER_* macros with TICKS() existing.
strobe support

long button presses now switch in/out of strobe