Use arena allocator (currently leaky!)

Expose ast via CG(ast)

Partial NS port (semicolon, no errors)

Port __TRAIT__ and __CLASS__ to AST

Port __METHOD__

Port __FUNCTION__ to AST

Handle trait __CLASS__ in parser

zend_stack_top() now returns pointer directly

Don't allocate zend_stack elements individually

Instead allocate a vector of elements. Size must now be specified
on initialization rather than on push.

Merge mainstream 'master' branch into refactoring
During merge I had to revert:
Nikita's patch for php_splice() (it probably needs to be applyed again)
Bob Weinand's patch

Merge mainstream 'master' branch into refactoring
During merge I had to revert:
Nikita's patch for php_splice() (it probably needs to be applyed again)
Bob Weinand's patches related to constant expression handling (we need to review them carefully)
I also reverted all our attempts to support sapi/phpdbg (we didn't test it anyway)

Conflicts:
Zend/zend.h
Zend/zend_API.c
Zend/zend_ast.c
Zend/zend_compile.c
Zend/zend_compile.h
Zend/zend_constants.c
Zend/zend_exceptions.c
Zend/zend_execute.c
Zend/zend_execute.h
Zend/zend_execute_API.c
Zend/zend_hash.c
Zend/zend_highlight.c
Zend/zend_language_parser.y
Zend/zend_language_scanner.c
Zend/zend_language_scanner_defs.h
Zend/zend_variables.c
Zend/zend_vm_def.h
Zend/zend_vm_execute.h
ext/date/php_date.c
ext/dom/documenttype.c
ext/hash/hash.c
ext/iconv/iconv.c
ext/mbstring/tests/zend_multibyte-10.phpt
ext/mbstring/tests/zend_multibyte-11.phpt
ext/mbstring/tests/zend_multibyte-12.phpt
ext/mysql/php_mysql.c
ext/mysqli/mysqli.c
ext/mysqlnd/mysqlnd_reverse_api.c
ext/mysqlnd/php_mysqlnd.c
ext/opcache/ZendAccelerator.c
ext/opcache/zend_accelerator_util_funcs.c
ext/opcache/zend_persist.c
ext/opcache/zend_persist_calc.c
ext/pcre/php_pcre.c
ext/pdo/pdo_dbh.c
ext/pdo/pdo_stmt.c
ext/pdo_pgsql/pgsql_driver.c
ext/pgsql/pgsql.c
ext/reflection/php_reflection.c
ext/session/session.c
ext/spl/spl_array.c
ext/spl/spl_observer.c
ext/standard/array.c
ext/standard/basic_functions.c
ext/standard/html.c
ext/standard/mail.c
ext/standard/php_array.h
ext/standard/proc_open.c
ext/standard/streamsfuncs.c
ext/standard/user_filters.c
ext/standard/var_unserializer.c
ext/standard/var_unserializer.re
main/php_variables.c
sapi/phpdbg/phpdbg.c
sapi/phpdbg/phpdbg_bp.c
sapi/phpdbg/phpdbg_frame.c
sapi/phpdbg/phpdbg_help.c
sapi/phpdbg/phpdbg_list.c
sapi/phpdbg/phpdbg_print.c
sapi/phpdbg/phpdbg_prompt.c

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Cleanup (2-nd round)

Fixed memory leak

Fixed suppor for multibyte encoding

Refactored ZVAL flags usage to simplify various checks (e.g. Z_REFCOUNTED(), candidate for GC, etc)

Changed data layout to allow more efficient operations

STR_DUP() doesn't duplicate interned strings anymore. In case new string is required STR_INIT() or STR_ALLOC() should be used.

Refactor mbstring (incompleted)

Fixed __FILE__ and __METHOD__ constants

Fixed memory leaks

Handle interned strings as non-refcounted scalars

Fixed memory leak in ext/standard/tests/strings/005.php

Fix non-zero terminated strings

Fixed __METHOD__ handling

Use better data structures (incomplete)

Use better data structures (incomplete; able to run bench.php)