As boost/timer.hpp is being deprecated, and the needed functionality
is very little, reimplemeted naively a timing class for the purpose
of measuring the test-unit time.

- specific timer class that is cross-platform and agnostic to changes made
  to the OS while measuring time (mac, posix and windows). Wall-clock and system/user
  time available
- changed framework to work fully with microseconds. Only ::alarm needs seconds
  and ceiling is used for signaling time-out
- Windows now signals also time-outs the same way as for other platforms (exception
  raised in the test and reported). However, Windows platform do not raise a signal
  that terminates the current test
- timeout is not used for failing a test-suite as well. Remaining time calculation is
  now made in microseconds. Adding an observer interface for signaling time out and
  adding the time outs in the test results
- cleaned up interfaces, clarify the code about the dimension of the different scalar values.