Remove some confusing assignments to NamedEntity::m_cachedClassOffset

Assigning this field is actually protected by the target
cache lock, and allocKnownClass does the assignment.
Get rid of variable break/continue

This is gone as of Zend 5.4: as far as I can tell, anything other than a
positive integer literal is a parse error (including constants, "1 + 1",
etc.) Let's get rid of it. The mere fact that this construct ever
existed in any programming language is deeply horrifying.

This lets us get rid of all the goofy code that subtracts 1 from the top
value on the stack, does IterFree if needed, and jumps to the next
level. Now, we can hardcode the necessary IterFrees and do a single
jump, right where the break/continue actually is.

The error message for using a non-integer expression is less helpful
than Zend's (Zend says "non-constant operand not supported"; ours is
"unexpected T_VARIABLE" or whatever). It wouldn't be that hard to do in
our parser, if we think that's helpful. I don't think it matters,
though.
Remove two unused builtin_functions.h things, collapse print() into echo()
Port debugger unit tests for break command to new framework

Port debugger unit tests for break command to new framework to prepare for added many more tests dealing with nested namespaces.
Check precondition before calling set_execution_mode

set_execution_mode has an assertion that amounts to a precondition requiring that its input parameters have been validated. This causes hhvm to assert and crash if the user specifies an invalid mode on the command line.
Delete reqLitHelper

It seems to have died with tx64.
use cpus+1 for tests

@swtaarrs says repo contention is a thing of the past and this is the right load to put on the cpu.
Remove less, more, and equal functions from Variant

Re-implement them in terms of TypedValue and Cell helpers.
Remove Variant::GetTypedAccessor

This stuff almost is an abstraction layer, but it's in a
strange place.  Also, the layout of TypedValue isn't something we've
been using through an abstraction layer, and if we want to later I
think we won't want to do so using this one.
Move the unwinder out of bytecode.cpp

Move all the stack unwinding code to its own module, delete
some redundant enumerations, document a few things.  Gets rid of most
of the remnants of the old setjmp/longjmp-based implementation at the
enterVM level but doesn't do much to the unwinder itself (coming in
separate diff to hopefully be easier to review).
Restructure the unwinder a bit; use visitStackElems and simplify some things

Hopefully a little bit simpler, and duplicating less logic
with Stack::toString.  Contains some fixes to visitStackElems to make
it work for this (it is printing some stacks slightly incorrectly
right now, too ... :)
RecursiveFilterIterator

simple
Verifier: Fix a typo in switch bounds checking
add config.hdf to large_memory test

This probably needs a repo to check repo contention
more robust test

horribly broken things don't emit json
PolicyArray: implement NOT_IMPLEMENTED methods

This implements the "last" unimplemented methods in ArrayShell. The sorting-related methods need no implementation because PolicyArray scales to HphpArray before sorting.
Revert "PolicyArray: implement NOT_IMPLEMENTED methods"

This reverts commit 1b65776a391188369a73dafca4851ba233e4e410.
Fix: Vector, Map, and StableMap should implement the Indexish interface
Translate gen_systemlib.php to bash

Remove another piece of PHP-dependant bootstrapping
use number of CPUs on machine for tests