Added a bunch of new tests for function approximation with different sample density - slows down the testing considerably since many densely sampled test functions are approximated
Added a bunch of new tests for function approximation with different sample density - slows down the testing considerably since many densely sampled test functions are approximated

ds283/splinter,bgrimstad/splinter,bgrimstad/splinter,bgrimstad/splinter,bgrimstad/splinter,ds283/splinter,ds283/splinter,bgrimstad/splinter,ds283/splinter,ds283/splinter