fix wrong selection probabilities, insert dummy thermal wavelength factor
fix bugs, do cleanup

- major bug fix: pbc check routines
- fix: Metropolis test -- update expected values
- fix: Wang Landau test -- update expected values. fixes #19
- code beauty: remove superfluous rng variable in test
- compatibility fix: switch to boost array for gcc backwards compatibility
- fix: new default debug compile options
- fix: make get_neighbours tests independent of iterator order
- fix: clean target in mcchd_wl Makefile
- code beauty: replace explicit types by typedefs in mcchd_wl