Fix building on MacOS (10.10 Yosemite)

[iJunkie22]

These changes make use of MacPorts-provided PySide, as HomeBrew has dropped support for my MacOS version (see bottom of post).
This is a very rough patch, so I am open to any corrections/comments about the coding style/names/etc.

PS: I did not see any contribution guidelines for non-bug-reports, so I hope this is okay!

brew install pyside
Updating Homebrew...
==> Auto-updated Homebrew!
Updated 1 tap (homebrew/core).
==> Updated Formulae
Updated 4 formulae.

Warning: You are using macOS 10.10.
We (and Apple) do not provide support for this old version.
You will encounter build failures with some formulae.
Please create pull requests instead of asking for help on Homebrew's GitHub,
Discourse, Twitter or IRC. You are responsible for resolving any issues you
experience while you are running this old version.

qt: macOS Sierra or newer is required.
Error: An unsatisfied requirement failed this build.

[Kadack]

Hello I can't open my world 1.16.3 in mcedit2 and mcedit1 i rinitialised my computer after i can't open any world was created in 1.15 and + idk for 1.14 i can open 1.8 save

An error occurred while opening C:\Users\user\AppData\Roaming.minecraft\saves\tr bedrock
'NoneType' object is not iterable

Traceback (most recent call last):
File "mcedit2\editorapp.py", line 790, in loadFile (self is a MCEditApp)
File "mcedit2\editorsession.py", line 419, in init (self is a EditorSession)
File "mcedit2\editorsession.py", line 724, in setConfiguredBlocks (self is a EditorSession)
File "mcedit2\editorsession.py", line 728, in reloadModels (self is a EditorSession)
File "src\mcedit2\rendering\blockmodels.pyx", line 236, in mcedit2.rendering.blockmodels.BlockModels.init
File "src\mcedit2\rendering\blockmodels.pyx", line 278, in mcedit2.rendering.blockmodels.BlockModels.loadModelParts
TypeError: 'NoneType' object is not iterable