Added a unit test for the double brackets SMILES bug

Change-Id: Ib956b78ba268c2ab8f452e70e4c0b619a5e774aa
Signed-off-by: John May <john.wilkinsonmay@gmail.com>
Determine earlier if the nitrogen needs an explicit implicit hydrogen (you know, like [nH], solving the double bracket problem

Change-Id: I32ab2374e403edd7c3cd5dc6656d6c94a1de0e3a
Signed-off-by: John May <john.wilkinsonmay@gmail.com>
Unit test that checks that implicit hydrogens on ring nitrogens are only added when they are negatively charged (bug #1300)

Change-Id: I2fc8c80eed751653a6d3e96b02ef0afbd60d81a5
Signed-off-by: John May <john.wilkinsonmay@gmail.com>
Fixed generation of SMILES with non-charged nitrogen rings with an implicit hydrogen (bug #1300)

Change-Id: I92720e88b167116c01b2d049ff8af55c833f1d21
Signed-off-by: John May <john.wilkinsonmay@gmail.com>