add eglReleaseThread
split AL/ALC errors
our one and only context should include a stencil buffer
add self to authors
Merge pull request #2533 from Daft-Freak/eglReleaseThread

Add stub for eglReleaseThread
clean up some old comments
document -v saving temp files; #2538
mention that .mem must be alongside .js
use compiler opts in -E, to use our target, system dirs, etc.; fixes #2534
Use typedefs in html5.h for referring to callback function pointers instead of passing the function pointer types in the function declaration to avoid Sphinx doc parser from getting confused during parsing.
Fix stackTrace() in preamble.js to support IE10 and IE11.
remove zlib headers from system/include
update csmith driver
document --memory-init-file on by default in opt builds in Changelog
Merge pull request #2544 from juj/stacktrace_js

IE stack trace fix.
testcase for #2539
add missing zconf.h in test suite
build enough of libcxxabi to support bad_typeid without undefined symbols; 1.21.5; fixes #2547
do not warn on malloc not present, we do so at runtime if used (+commented code to pull in malloc and other system libs based on EXPORTS)
update sanity.test_emcc_caching