make convert_loops_to_sites more strict?

[gfudenberg]

looplib/looplib/looptools.py

Line 30 in 0ea23c8

else:

is there a reason for allowing two lists to be passed? cc @golobor

convert_loops_to_sites also has a failure mode for n=2. My previous solution was not very elegant...

looplib/looplib/looptools.py

Line 16 in d9dedda

if specifyVerticalArray==True:

. Perhaps this aspect of autodetection can also just be disabled?

[gfudenberg]

how bad would it be to assume that loops are always numpy arrays? (and deprecate lists of tuples)