Bring static scalar AST more in line with normal AST

Const eval unary pm (as previously)

Implement constant expression folding as a separate pass

Support string interpolation

zend_ast_dynamic_ast returns new node

AST stage 2.4

Add ability to specify additional attr in AST

Make ast->children a uint

Future optimization: only use uint for dynamic lists and use a
uchar or even an introspection function to get the child count.

AST stage 1.9

Expressions (mostly) use the AST

AST-based compiler: Stage 1

Remove (&ast->u.child)[i] weirdness

Re-applyed Bob's patch with minor fixes

Reverted Bob's patch (it breaks many tests when run with opcache and needs to be fixed first).

Re-added fix for bug #66015 and adapted for phpng branch

Fix bug #66015 by reverting "Removed operations on constant arrays."

Use better data structures (incomplete)

Use better data structures (incomplete)

Bump year

Fixed bug #66252 (Problems in AST evaluation invalidating valid parent:: reference. Constant expessions have to be evaluated in context of defining class).

Moved arrays again to "static_scalar:" & little cleanup

Renaming

Constant expressions refactoring

Fixed mem leaks, added tests and ternary operator

Working commit for constant scalar expressions (with constants).
Tests will follow.