Refactor class name resolution as well

Refactored parameter passing mechanism.

In PHP-5.6 and below each argument passed to user function was copies on VM stack twice.
Now we always have ZEND_INIT_FCALL (or simular) opcode th

Refactored parameter passing mechanism.

In PHP-5.6 and below each argument passed to user function was copies on VM stack twice.
Now we always have ZEND_INIT_FCALL (or simular) opcode that pushes "call frame" on top of VM stack.
"Call frame" is actually the same zend_execute_data structure.
All the following ZEND_SEND instructions push arguments on top of the stack in a way that they directly comes into corresponding CV variables of the called frame. Extra arguments are copied at the end of stack frame (after all CV and TMP variables) on function enterance.

There are two minor incompatibilities:
1) It's not allowed to decalre functions redefining arguments e.g. "function foo($a,$a) {}".
2) func_get_arg() and func_get args() return the current value of argument and not the original value that was sent.

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Some refactoring of fn/const resolution

Drop dead code

Implement constant expression folding as a separate pass

Support string interpolation

Remove dead code

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.

Remove dead code

AST stage 1.9

Expressions (mostly) use the AST

AST-based compiler: Stage 1

LTR static member access

Change precedence of $ operator

$$foo['bar'] is now interpreted as ${$foo}['bar'] rather than
${$foo['bar']}.

Introduced immutable arrays. They don't need to be copyed and may be used directly from SHM.

Refactor MySQLi (incompleted, only compilable now)

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

Redesigned zend_execute_data layout now EX(object), EX(scope) and EX(called_scope) arr properties of the current function execution co
ntext. They are set during zend_execute_data initialization

Redesigned zend_execute_data layout now EX(object), EX(scope) and EX(called_scope) arr properties of the current function execution co
ntext. They are set during zend_execute_data initialization and never changed.

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Use symbolic names instead of magic constants + optimization

Pass expected array size hint in INIT_ARRAY

To avoid unnecessary rehashes

Fixed compilaation warnings

ZEND_SEND_* optimization