Update references to RedHat

[lucaswerkmeister]

Referring to the compiler as “the RedHat compiler” doesn’t really work anymore, following the migration to the Eclipse foundation. Do we call just say “Eclipse” instead now (e. g. “an Eclipse AST AndOp”)? Or is there some better name we can use?

Scope:

• ceylon.ast.redhat, test.ceylon.ast.redhat module names
• RedHatTransformer class name
• documentation comments scattered around ceylon.ast.redhat and test.ceylon.ast.redhat
• README
• where else?

[lucaswerkmeister]

On the other hand… Ceylon isn’t Java. I don’t have the impression that there are chances of a different, independent compiler for Ceylon coming up anytime soon. So perhaps it would make sense to ignore the vendor and just talk about “the compiler AST”. Does that sound reasonable?

[gavinking]

Yes, definitely.

[davidfestal]

and then a truffle / graal AST ?