Fix #165 Use Corrected CFL Criteria

### Use Reference that corrected Yee's Paper

[A. Taflove & M. E. Brodwin](http://www.ece.northwestern.edu/ecefaculty/taflove/Paper2.pdf)
IEEE Trans. on Microwave Theory and Techniques, August 1975
Formula (7)

- refactored InitialiserControler to use the (default enabled) PHYSICS log state
- removed "can not restart from hdf5 dump" check since this is outdated with checkpoints

### Notes

Our "old" implemented CFL was not *wrong* in the sense of *stability of the algorithm*.
But it was *too conservative* for many cases that used non-cubic cells. This conservatism in turn causes numerical dispersion and should therefore be avoided.
In other words: stay as close as possible to the CFL with your time step to cell "ratio".