beremiz

SVGHMI: changes that should fix some corner cases about unlinking and discardable element that still didn't show until now.
- list that would have been declared in some groups could have been discarded.
- elements to be unlinked were comuted based on filtering $hmi_elements, whereas $hmi_widget already filtered list
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
```