Conform to pep8 and pylint :

pep8 version: 2.3.1
./ConfigTreeNode.py:130:49: E231 missing whitespace after ','
./editors/Viewer.py:643:24: E128 continuation line under-indented for visual indent
./editors/Viewer.py:670:12: E221 multiple spaces before operator
./editors/Viewer.py:671:13: E221 multiple spaces before operator
./editors/Viewer.py:2138:52: E203 whitespace before ':'
./editors/Viewer.py:2139:66: W291 trailing whitespace
./controls/VariablePanel.py:154:25: E231 missing whitespace after ','
./controls/LocationCellEditor.py:88:1: W293 blank line contains whitespace
./controls/LocationCellEditor.py:191:25: E221 multiple spaces before operator
./controls/LocationCellEditor.py:200:17: E128 continuation line under-indented for visual indent

pylint 1.8.3,
************* Module controls.LocationCellEditor
controls/LocationCellEditor.py:200: [C0330(bad-continuation), ] Wrong continued indentation (add 9 spaces).
_("Selected location is identical to previous one"))
^ |
************* Module controls.VariablePanel
controls/VariablePanel.py:154: [E1601(print-statement), VariableTable.SetValue] print statement used
************* Module editors.Viewer
editors/Viewer.py:643: [C0330(bad-continuation), ] Wrong continued indentation (add 1 space).
self.GetAddMenuCallBack(self.AddNewComment))
^|
editors/Viewer.py:598: [W0612(unused-variable), Viewer.AddDivergenceMenuItems] Unused variable 'add_branch'
editors/Viewer.py:1655: [E0602(undefined-variable), Viewer.PopupConnectionMenu] Undefined variable 'variable_type'
editors/Viewer.py:1649: [W0612(unused-variable), Viewer.PopupConnectionMenu] Unused variable 'connection_type'
************* Module connectors.PYRO.PSK_Adapter

How Do I Submit A Good Pull Request?
----------------------------------

It's highly recommended to write nice and clean python code. Beremiz
project tries to follows most of PEP-8 recommendations. They are
automatically checked on every push and merge by Bitbucket pipelines.

To avoid pushing "unclean" code, i's recommended to add one of the following
commands to pre commit Mercurial hook into .hg/hgrc configuration file.

Unfortunately script can't distinguish between real commit and shelve. If you
are using shelve (or maybe some other affected commands), it's recommended to
use pre-<command> and post-<command> hooks to create flags to skip checks on
some operations.


```
[hooks]
pre-shelve.linter = touch .hg/skiphook
post-shelve.linter = rm .hg/skiphook
pretxncommit.linter = ./tests/tools/check_source.sh --only-changes
```
or the same done using Docker container, so result will be the same as
on Bitbucket pipeline.

```
[hooks]
pre-shelve.linter = touch .hg/skiphook
post-shelve.linter = rm .hg/skiphook
pretxncommit.linter = hg status -m -n -a -n -I '**.py' --change $HG_NODE > files.lst && docker run --volume=$PWD:/beremiz --workdir="/beremiz" --volume=$PWD/../CanFestival-3:/CanFestival-3 --memory=1g --entrypoint=/beremiz/tests/tools/check_source.sh skvorl/beremiz-requirements --files-to-check files.lst
```