Add fail() to assertions class
Add are_equal for doubles
Changes in this version:

* Scoping rules changed - FIXTURE macros are now namespaces, while
  TEST macros are locally scoped - This means that both variables
  and functions can be added to a test fixture.
* Time is measured on all levels (harness, fixture and test) - Also,
  in a correct way instead of adding the sum of the time for all
  tests/fixtures
* SETUP and TEARDOWN macros
* A brand new console/terminal reporter (with pretty colours!)
* Some new assertions (fail() and a couple of explicit non-templated
  are_equal)