Remove multithreading and fix measurement timing.
Remove multithreading and fix measurement timing.

Measurements start on well-defined cycles without multithreading using
modulo. This removes a lot of complications with logging/debugging etc.
It also enables to use only one db manager instance. Remove separate
write function as unneeded, but leave it in place for dummy writing to
handle filenames etc.

mgunyho/kiltiskahvi