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
Merge pull request #1403 from imvu/scons-updates-pull-request

Bring SCons integration up to date with latest incoming and fix some SCons build reliability issues and races