Use astDumpPrettyVersion() instead of emitAst() to dump versions/targets
emit: Make emitAst() private
emit: Remove VERBLOCK/TARGETBLOCK emitting

They'll always be turned into #if blocks by the AST now, and for debugging
there is astDump().
emit: Simplify emitType() for use on ASTNODE
ast: Remove useless 0 and x folding check

It should already be handled by the const-lhs-swap-to-rhs and x-and-0
checks. The comment there didn't mention the & AND op either...
ast: Preserve oct/hex flags during CONST folding
ast: Split CONST into CONSTI and CONSTF

- Lots of code simplified, can now check CONSTI/CONSTF in parallel instead
  of having to check for CONST and then typeIsFloat(). And especially the
  const folding code only uses CONSTI and can now completely ignore CONSTF.

- Some of the old code was using CONST.vali without checking typeIsFloat()
ast: Add astIsCONSTI()