Update generated_files.sh to no longer build system/gen

Also split constants.h and class_map.cpp into separate generates.
Revert "[ext_asio] Use guard to make sure state is restored correctly"
Fix type mistake in cgOpSub

Sometimes src1 isn't an int. This was causing failed asserts
in debug perflab runs.
Eliminate int32, uint32, int16, uint16, int8, uint8.

This concludes the inttypes replacement.
These replacement have been mostly mechanical
with the use of cxx_replace.
Move enter/exit context responsibility from PHP to join(), try #2

Move the responsibility of entering/exiting contexts from PHP to the
implementation of $wait_handle->join().

This eliminates possibility of weird situations, like contexts without
any running wait handle. This guarantees that asio_get_current() returns
null only if called completely out of asio framework and simplifies some
logic, such as getCurrentWaitHandleDepth().
Keep track of WaitableWaitHandle creators

Keep track of creator that constructed us.
Expose reflection thru API

Expose the following data to the PHP:
- asio_get_current_context_idx(): get current context index
- asio_get_running_in_context(): get running wait handle in a given context
- asio_get_running(): get running wait handle in a current context (renamed asio_get_current())
- WaitableWaitHandle::getContextIdx(): get context the wait handle operates in
- WaitableWaitHandle::getCreator(): get continuation wait handle that constructed this wait handle
Implement Switch in IR
const bool hhvm is dead
Reset Xbox threads after each request

Xbox threads can now release memory after each request. Also
gives cleaner semantics as Xbox requests dodn't have to be careful
about not modifying global state.
Revert allowing $this in closures

I'm going to do a replacement diff anyways, so all this does is delays it a week.
provide better debugging information if source.size != dest.size
fix bytecode spec
increase readability of 0 -> KindOfUninit

I was perplexed by this. It makes more sense to me this way.
handle create_function with a closure in it

This actually was pretty broken already. If you defined a new function in the ##create_function## string it would return that function but it wouldn't move it to the right unit so it can't execute. A big mess. For example:

    $ cat a.php
    <?php
    $a = create_function('', 'function b() { return 3; }');
    $a();
    var_dump(b());
    $ php a.php
    HipHop Fatal error: Undefined function: b in /data/users/ptarjan/hphp/hphp/a.php on line 4
    $ hhvm a.php
    int(3)
Revert "make debug_backtrace go through ignored functions"
capitalize Closure

PHP is case insensitive, but this leads to better debugging messages if the case matches the declaration.
get ref correct in closure parser
pass 'this' through generators

I think this was just an oversight for generators. They should pass all the attributes inside.
add zend_closure_020

A good unit test that I think we should have.