Bug on Build when Make pk1 to different valence

[zhongxiang117]

The bug is on when using Build change pk1 valence.

Reproduce:

• load any molecule
• pick two atoms
• ExternalGUI -> Build -> Make (pk1) Positive

The error will be:

PyMOL>alter pk1, formal_charge=0.
Traceback (most recent call last):
  File "/MY/BUILD/PYMOL/PATH/lib/python/pymol/editing.py", line 1472, in alter
    return _cmd.alter(_self._COb, selection, expression, False, int(quiet), dict(space))
  File "", line 1, in <module>
TypeError: 'float' object cannot be interpreted as an integer

Reason:

By checking the info, we know that this error is caused by the float and int conversion, and we notice that predefined expression, formal_charge=0. (end with a period) is wrong.

Fix:

Checking the codes:

Path: master -> modules -> pymol -> _gui.py L230-L232
Link: https://github.com/schrodinger/pymol-open-source/blob/master/modules/pymol/_gui.py#L230-L232

                ... # original
                ('command', 'Make (pk1) Positive [Ctrl-Shift-K]',   'alter pk1, formal_charge=1.'),
                ('command', 'Make (pk1) Negative [Ctrl-Shift-J]',   'alter pk1, formal_charge=-1.'),
                ('command', 'Make (pk1) Neutral [Ctrl-Shift-U]',    'alter pk1, formal_charge=0.'),

The int number should be used, then:

                ... # update
                ('command', 'Make (pk1) Positive [Ctrl-Shift-K]',   'alter pk1, formal_charge=1'),  # no period
                ('command', 'Make (pk1) Negative [Ctrl-Shift-J]',   'alter pk1, formal_charge=-1'), # no period
                ('command', 'Make (pk1) Neutral [Ctrl-Shift-U]',    'alter pk1, formal_charge=0'),  # no period