Replace operator-related nodes by AstFactory methods.
Remove usages of SymbolEntry in AST.
Add new AST node AstPostExpression to implement post increment/decrement operations in a generic fashion.
Passes compiler/parser tests, fails VMTests.
Fix bug in code generation for global variable initialization.
VMTests run successfully on Prexonite VM.
Update broken usages of ast("BinaryOperator",...) in favour of ast3("BinaryOperation",...)