aarch64 bug in version check.

[uDude]

Note I will issue PR.

Platform: linux/aarch64
Python: 3.8

Replicate bug:
install via 'pip' following instruct on github.
Try to create involute gear and have red error msg on window footer. Contents of message:

"Oct 28 12:15:15 n2 org.mate.panel.applet.BriskMenuFactory[46424]: invalid literal for int() with base 10: '18.4'Running the Python command 'CreateInvoluteGear' failed:"

Check should reed: int(float(....)) since version string is float string.

Note: issue relate to #63. Mac version only 18.x so fix this bug and change version to >= 18 in following PR fix both.

[jbaehr]

I have just checked an old 0.18.4 here on macOS 10.14 and I cannot reproduce it. Creating gears, without #85, works just fine. So I do not think #63 is related. I'd rather investigate where the version constant in your build comes from. What does the following give on your build in the FreeCAD's python console?

>>> App.Version()
['0', '18', '16146 (Git)', '/Users/distiller/miniconda3/conda-bld/git_cache/github.com/FreeCAD/FreeCAD', '2019/10/22 16:53:35', '(HEAD detached at 0.18.4)', '980bf9060e28555fecd9e3462f68ca74007b70f8']