Added missing #include line so that it now does compile.

Cells now initiated to use normally distributed displ. step
with params rather close to the HeLa Mitocheck dataset (provided
delay between frames is cca 30min).
M    src/cell.h

Added some DEBUG reports to study RndWlk behaviour better.
M    src/cellScm.cpp

Added support for the normally distributed displacement vectors.
M    src/toolbox/randWalk.h