Fix #206: Null coalescing operator on Vector make search failed

This happens because php_ds_vector_read_dimension makes a REF from the value
when type is not BP_VAR_R. So when the type i

Fix #206: Null coalescing operator on Vector make search failed

This happens because php_ds_vector_read_dimension makes a REF from the value
when type is not BP_VAR_R. So when the type is BP_VAR_IS then we see the first
element becomes a reference. You can see this when doing var_dump.

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review object management

Fix array access

First steps to PHP 8 support

Fix null coalesce access

Refactoring of php subdirectory prefixes

Add all gc handlers

Minor refactor of vector clear and realloc

Fix object release memory leaks #30

Object renames, priority queue updates

Rebased

Significant include refactor, htable renaming

Significant rename to split ds from php