cleanup: pylint, W0109 # (duplicate-key) Duplicate key 'X' in dictionary

Add python3 syntax checking to CI

Fix old style exception raise and exec syntax

Use python 3 compatible exception syntax everywhere

cleanup: pylint, R0123 # (literal-comparison) Comparison to literal

Use predefined constants for PlcStatus instead of string literals

cleanup: pylint, R1704 # (redefined-argument-from-local) Redefining argument with the local name 'Y'

cleanup: pylint, R1701 # (consider-merging-isinstance) Consider merging these isinstance calls to isinstance(CTNLDFLAGS, (str, unicode))

cleanup: pylint, E1304 # (missing-format-string-key) Missing key 'X_name' in format string dictionary

cleanup: pylint, E1300 # (bad-format-character) Unsupported format character '"' (0x22) at index 17

cleanup: pylint, W0111 # (assign-to-new-keyword) Name async will become a keyword in Python 3.7

cleanup: pylint, E1310 (bad-str-strip-call) Suspicious argument in str.strip call

Fix segmentation fault when last lines in text POUs should be highlighted

enable etherlab checks

resort enabled pylint check to move likely-most invasive changes to the end

clean etherlab: pylint, C0330 # (bad-continuation) Wrong hanging indentation before block

clean etherlab: pylint, W0612 # (unused-variable) Unused variable 'X'

clean etherlab: pylint, W1618 # (no-absolute-import) import missing `from __future__ import absolute_import`

clean etherlab: pylint,E0602 # (undefined-variable) Undefined variable 'X'

clean etherlab: pylint, E1136 # (unsubscriptable-object) Value 'X' is unsubscriptable

ignore missing MotionLibrary

to fix pylint error 'E0401 # (import-error) Unable to import 'X'

clean etherlab: pylint, E0611 # (no-name-in-module) No name 'X' in module 'Y'

clean etherlab: pylint, C0123 # (unidiomatic-typecheck) Using type() instead of isinstance() for a typecheck.

clean etherlab: pylint, W0104 # (pointless-statement) Statement seems to have no effect

clean etherlab: pylint, W0631 # (undefined-loop-variable) Using possibly undefined loop variable 'X'

clean etherlab: pylint, C1001 # (old-style-class) Old-style class defined.

clean etherlab: pylint, W0611 # (unused-import) Unused import X

clean etherlab: pylint, E0102 # (function-redefined) method already defined

clean etherlab: pylint, W0105 # (pointless-string-statement) String statement has no effect