Alignment issues in Macrocyles from two building blocks.

When making a Macrocycle from only two building blocks, there is no handling of edge assignment when both edges are on the same position (calculated in Macrocyle.py on init based on the number of bbs in the chain).

MWE on my machine shows crossing bonds:

import stk

bb1 = stk.BuildingBlock(
    'BrCCOCc1ccc(COCCBr)cc1',
    functional_groups=[stk.BromoFactory()],
)
bb2 = stk.BuildingBlock(
    'BrCOBr',
    functional_groups=[stk.BromoFactory()],
)
macrocycle = stk.ConstructedMolecule(
    topology_graph=stk.macrocycle.Macrocycle(
        building_blocks=(bb1, bb2),
        repeating_unit='AB',
        num_repeating_units=1,
    )
)
macrocycle.write('macrocycle.mol')

[lukasturcani]

Your second issue is probably a duplicate of #15

[andrewtarzia]

Done!