add easy access in system class to max_n_mimima in database

for example:
system.params.basinhopping.max_n_minima = 1000
change cpp part to take integer template parameter for boxdim, change cpp tests accordingly
change wrapping of HSWCA to take integer templ arg forboxdimension
Merge pull request #63 from kjs73/hswca_boxdim_templ

HS_WCA use integer template arg for boxdimenison