Poor generated 3D structures

[avirshup]

We're getting clashes and overlaps in the generated 3D structures for big complicated ring systems.

To wit:

artim = mdt.from_inchi('InChI=1S/C15H22O5/c1-8-4-5-11-9(2)12(16)17-13-15(11)10(8)6-7-14(3,18-13)19-20-15/h8-11,13H,4-7H2,1-3H3/t8-,9-,10+,11+,13-,14-,15-/m1/s1')')
artim.draw()

gives

Need to detect these as soon as they're generated (and ideally have fallbacks), otherwise they will generate difficult-to-debug downstream errors.