PS: Thinking of it now, is the makefile really necessary? Why not just create emcc build method in TheIDE?
I would welcome that!
Note however that right now, there is intrinsic issue with emscripten and U++: Based on Javascript, emscripten inherits HTML5 runtime model, which basically does not allow (long story short) "Ctrl::Run" to exist...
So if ever we would want to support it, we would need "loop-less" mode for U++.
(Plus of course, half of Core would have to be made inactive...)