add easy access in system class to max_n_mimima in database

for example:
system.params.basinhopping.max_n_minima = 1000
Merge pull request #63 from kjs73/hswca_boxdim_templ

HS_WCA use integer template arg for boxdimenison
Merge remote-tracking branch 'origin/master' into hswca_cell_lists
add more cpp tests, todo: fix problems in neighbor iterator, add debug output