[Haxe] Support of -D display-stdin

[SlavaRa]

HaxeFoundation/haxe#5120

[SlavaRa]

WIP

[Neverbirth]

With WIP you mean you are looking into it?

[SlavaRa]

I did support for the PostfixCodeCompletion , and now plan to make support for the editor, I'll be ready to do PR on this week.
This eliminates the need to save the file for each action

[Neverbirth]

Good one, although I have to admit I got used to the automatic saving and now I like it heh. IJ does it too for every project.

[SlavaRa]

those who use the editor via CrossOver complain that the permanent saving create problems((

[elsassph]

We really want to avoid this saving for sure. But careful keeping backwards compatibility - some people here still use Haxe 3.1.3!

[SlavaRa]

depending on the compiler will operate in different modes ))