Migrate to Antlr4

[hazzik]

Antlr3 is no longer actively maintained and it would be nice if we can migrate to Antlr4 instead.

[danilobreda]

What is the difference between ANTLR 3 and 4?

[Jetski5822]

Oh yeah - this would be awesome - as the other project is EOL.

[SymbioticKilla]

Any ETA? .NET Standard 1.6 in Antl3 is not nice :(

[hazzik]

Somewhere between 700 billion and a trillion 300 million billion years.