fix pylint warning '(pointless-string-statement) String statement has no effect'

Python doesn't support docstring for variables directly. Where
appropriate Sphinx style for docstrings for variables is used
'#: some-docstring'

fix error __init__ method from base class is not called

fix more than one statement on a single line

fix ungrouped imports from package X

fix unnecessary lambda and enable corresponding pylint check

fix wrong-import-order. first standard modules are imported, then others

fix (old-style-class) Old-style class defined error for most parts of
the code

only PyJS code is left, because it does some fancy tricks and can't be
easily fixed. So far PyJS doesn't support Python3 anyway.

remove in-tree version of Zeroconf and use upstream from
python-zeroconf package

remove reimported modules

fix unnecessary parens after keyword

enable pylint checker

so far only print statement is checked

fix usage of python2-only print statement

run python tests with non-english locale to catch bugs related to localization

make it possible to update XSD schema in project controller after new
target PLC is added or removed.

For example:


...
import targets
targets.targets["PLC"] = {"xsd": os.path.join(self.customBeremizPath, "PLCtarget", xsd),
"class": lambda: PLC_target,
"code": {"plc_PLC_main.c": os.path.join(self.customBeremizPath, "PLCtarget", "plc_PLC_main.c")}
}

from ProjectController import ProjectController, GetProjectControllerXSD
ProjectController.XSD = GetProjectControllerXSD()

fix commit "lazy initialization of highlight pens and brushes
for DebugVariableViewer" (5562f34f)

clean build example project after running test

fix problem if DataTypeEditor was imported before localization is
loaded

That doesn't affect systems with english locales.

add shell script to run all python tests and automatically handle Xvfb

add PLCOpenEditor tests

run application tests in full screen mode

clean sys.argv, because if test is running from pytest
sys.argv contains string "pytest --timeout 0 ./tests/tools"
Beremiz application parses it and throws exception.

rework Beremiz application "testCheckProject" test to allow easier reuse later

add application name for PLCOpenEditor

This is needed to work user configuration load/store, if PLCOpenEditor
is launched from test environment.

rewrite PLCOpenEditor. Add PLCOpenEditorApp class for easier customizations.

lazy locale initialization

wx.Locale() can't be called without wx.App. So don't call it at
import. It makes PLCOpenEditor simpler.

use CustomIntCtrl instead of wx.SpinCtrl because it doesn't support
long integer needed for UDINT, (U)LINT types.

This commit complements commit 74a3f4d "fix LINT and ULINT ranges".

add custom TextCtrl allowed to enter long integer with bounds checking

It's needed because wx.SpinCtrl supports only 'int' type. For UDINT
and (U)LINT long type is necessary.

use pytest for testing

run separate test on every project instead of one big long test all projects

move configuration for test environment into separate file conftest.py