Fluctuation of bins uses zero-seed random generator

[Thomas Latham]

The methods in the various histogram classes that perform the fluctuation of the bins within their uncertainties currently use LauRandom::zeroSeedRandom(). While this means that you don't have to manually set the seed to get a new set of fluctuations it means that you get a new histogram literally every time you run the program. This potentially causes problems because for each histogram you will likely want to perform many fits with randomised starting values of the isobar parameters. Attempting to do this will currently give you a different histogram in each of these randomised fits. Changing this to use LauRandom::randomFun() means that users will have to use LauRandom::setSeed(...) to change the seed when they want a different set of fluctuations. This will need to be included in the documentation for any function where fluctuateBins is an argument.

[Daniel Craik]

(In [94]) Changed histogram classes to use seeded random number generator for fluctuation and raising or lowering of bins and updated doxygen. closes #22