misc ungetc fixes
Added support for loading .ogg audio files using a combination of
`SDL_RWFromConstMem()` + `Mix_LoadMUS/WAV_RW()`.

`SDL_RWFromConstMem()` now returns an opaque reference that corresponds
to a Javascript-side object which retains the information passed in.
The same for `SDL_RWFromFile()` but it saves different information.

When `Mix_LoadMUS/WAV_RW()` is called, it now expects a reference to
one of those Javascript-side objects and from it, either uses a
pre-loaded Audio, or reads bytes from the file-system to make one,
or uses the bytes originally passed into `SDL_RWFromConstMem()` to
create one.

Note that with this change you can now simply embed sound files in your
app, you do not need to preload them.
update relooper comment
Updated with kripken's suggestions.
Made sure that `IMG_Load_RW` is also aware that it should receive
`SDL_RWops *` generated from `SDL_RWFromFile()`.
Merge branch 'incoming'
Implement SDL_Surface refcounting
fix test_static_link
Fix SDL_surface refcount test and initialise refcount to 1
Improve error message to better describe a user error with positional arguments.
Fix scons tools to use os.path.join so that windows paths don't have an exectutable name 'dir1\dir2\dir3/clang', which fails.
Blow away the jscache when embind changes and fix a cpppath dependency error when compiling embind files.
The emscripten metabuilder only builds three individually-named targets.  It's up to the caller to decide which variant to load.
the compress js optimizer pass is gone, replaced with minifyWhitespace
avoid importing shared from emscripten.py if possible
fixed stderr output to use printErr
Fixes in pread()

The bug occurs when pread() doesn't return 0 when asked to read an
offset beyond its buffer.

This behavior is explicitly documented at:
http://pubs.opengroup.org/onlinepubs/000095399/functions/read.html

> If the starting position is at or after the end-of-file, 0
> shall be returned
fix glGetAttachedShaders
Touched up formatting.
No functional change.
Formatting cleanup.