Start working on a version which only refcounts ref-data objects
Remove a lot of assertions which no longer apply.

JIT does not work. Wordpress appears to mostly work in interpreter
mode
Disable tests which depend on precise destruction

Might want to rewrite these (or, indeed, part of the test script)
so that they work again in the future.
Rewrite the test suite so that object IDs in var_dumps are ignored

Removing precise destruction means that object IDs can no longer
be identical to what is expected by zend. This is not a bug, so
I'm rewriting the test cases so they can continue to be useful.

The python script used can be seen at
https://gist.github.com/tgsergeant/5189e02bc934db9e2210
Try and make the JIT ignore all reference counts except for RefData
Remove errant release calls

If we block-allocate an object, we have to make sure it's not being
released through the conventional means. If it is, it's going to
end up on a freelist, and then could be double-allocated later on.
Initial work on a tracing garbage collector
Further attempts to trace the heap
Appear to be successfully tracing the heap
Cleaned up tracing
Change MarkSweepCollector to a thread-local singleton
Start to add new block-based memory management API
More work on block allocator
Block allocator working successfully.

Tests appear to mostly be working
Attempt to remember objects which have destructors
Cleanup of previous commit
Align GC-enabled slabs to a known value

This will make garbage collection easier, as we can
quickly tell what block an address belongs to
Add check to fix segfault in tracing-collector.

Not sure what was causing it at this stage.
Tracing collector marks which blocks are in use.

Next step is to be able to figure out what blocks have been used,
but are now garbage. We can then return them to the allocation
queue.
Port changes from the tracing branch.

Blocks are now marked as allocated, so the garbage collector is
able to determine what blocks need to be freed.