Handle Spiget api errors, use best-practice, disable incompatible code

[smcclennon]

Changes

install_requirements.py

• Use python3 -m pip instead of pip when installing on posix operating systems, as documented here.
• If an exception occurs, display the exception detail to the user alongside the troubleshooting suggestion.

src/plugin/plugin_updatechecker.py

• Handle Spiget api request errors, instead of crashing due to erroneously handling the unexpected data structure: {'error': '', 'msg': ''}. Further detail can be found in the commit description.

src/utils/console_output.py

• Don't attempt to change the console title on non-Windows systems to prevent an unexpected command error message from being displayed.

[Neocky]

Hey @smcclennon, thank you so much for your PR! 😃 Your changes will be included in Version 1.7.2! Have a good day! 👋

[smcclennon]

Thank you.

I rely on pluGET for several servers so I'm pleased the API crash is now patched :)