Currently .isNull is used, to detect icon validity, but such method doesn't take the file path detection into an account. Result being a lot of messages outputted to the Report view and fallback icon not being used.
This PR fixes such icon path related issues.
Renamed GDML Worbench icon from "GDML_worbench.svg" to "GDML_worbench_icon.svg" because while building FreeCAD the compiler requires "GDML_worbench_icon.svg"
Correct crash when Macro description is not reachable
Python crashed when under proxy - Macro list is charged - Proxy is undone ( internet connection lost) - Try to load macro description (u=None)
Add Proxy setting in Addon Manager Option UI
Correction of SSL context
Replace ssl.Purpose.CLIENT_AUTH by ssl.Purpose.SERVER_AUTH as context for a client
Add configuration of proxy setting UI
Add proxy management by urllib
Make the Addon Manager GUI friendlier by adding more color and uniformity to the UI for Addons that have a: pending-update, no-update, or are obsolete.
Manually created this .svg file. This PR also fixes a previous commit typos for AirplaneDesign and A2plus workbenches that fail to make them display correctly in the AddonManager GUI
Followup to PR #2369
* made appropriate addons/wbs lowercase
* used the correct case-sensitive spelling and formatting for addons/wbs
* updated .qrc file
* removed glider wb icon and mention in .qrc
