Separate GLSLANG_WEB (min-size build) and Emscripten options

Allows building non-min-size builds with Emscripten.
Adds ENABLE_GLSLANG_WEB_DEVEL.
Moves the glslang.js files to OSDependent/Web.
Small cleanups and docs update.

glslang/updateGrammar

@@ -1,4 +1,4 @@
-#!/usr/bin/bash
+#!/bin/bash
 
 if [ "$1" = 'web' ]
 then