Remove PluginContainer and TerrariaPlugin.Game

[MarioE]

There's not really a need for PluginContainer. The Main instance is also not very useful, so we should just scrap it and the constructor.

[hakusaro]

👍

[QuiCM]

👍

[AxisKriel]

👍

[QuiCM]

Is this still a thing?

[hakusaro]

@QuiCM this is the first issue on the TSAPI repo. I'm assuming the answer is "not really relevant" if anything.

[QuiCM]

Following the link to Pryaxis/TShock#919, it seems this was never acted upon