don't do this string manipulation unless debug is on
instead of using just the intrinsic name, add the '%' to the create_instrinsic/is_intrinsic calls.  cuts down on string interpolation costs

also clean up all the boolean valued intrinsics in compiler.coffee
ignore .plist files
add IRBuilder.createOr
remove the -d flags from the compile lines to cut down on the spew, and also remove some llvm libraries that we obviously don't need
switch to stderr for this spew
switch set from coffee to js
switch stack from coffee to js
big time optimization work

a few large changes that drop stage2 compile time from 4 minutes down to 1m25s.
node (stage1) still wins on my laptop here at 45s, but the gap is closing.

1) property maps now just store the ejsval strings instead of jschar*'s.  This
   means we need another deref to reach the jschar*'s for string comparisons, but
   it also means that for property iterators we don't have to create strings for
   each prop name every time.  Huge win.

2) comment out some of the 'debug.log ->...' usage in nodevisitor.coffee.  every
   time we end up in that function (i.e. on every node) we create new instances of
   the anonymous functions.

3) switch away from the different traversal classes (TreeTransform/TreeVisitor), to
   a single model that by default modifies in-place, but that works just fine if you
   return a new instance from the @visit* methods.

4) it turns out we didn't need the deep_object_copy SubstituteVariables, since we then
   walked the list allocating new objects anyway.  This was *huge* when it comes to
   string allocations, because JSON.parse/JSON.stringify is murderous with string
   allocations at the moment.

Not related to performance at all, but this commit also ended up containing the 'this'
binding for ES6 arrow functions.
make @opencode_intrinsics an object literal, and put all the flags in there
turns out visitArray needs to both flatten and filter.  yuck
move ReplaceUnaryVoid to optimizations.coffee.  also a few changes to SubstituteVariables.
the version of escodegen we're using doesn't support ES6 classes yet, so we need to disable the pre-class-desugaring output
add rudimentary ES6 class support as a desugaring step before closure conversion