0032065: Samples - use MODULARIZE within WebGL sample

Fixed multitouch input.

Module is now exported with global functions hidden via MODULARIZE
as global object OccViewerModule created by createOccViewerModule().
Global Module setup has been moved to occt-webgl-viewer.js.

Use EMSCRIPTEN_KEEPALIVE attribute istead of listing C functions via EXTRA_EXPORTED_RUNTIME_METHODS.
WasmOcctView now exports static methods as Module functions using EMSCRIPTEN_BINDINGS.

Standard_ASSERT_DBGBREAK_() is now defined using emscripten_debugger().

samples/webgl/occt-webgl-viewer.js

@@ -0,0 +1,28 @@
+var OccViewerModule =
+{
+  print: (function() {
+    var anElement = document.getElementById('output');
+    return function(theText) { anElement.innerHTML += theText + "<br>"; };
+  })(),
+  printErr: function(theText) {
+    //var anElement = document.getElementById('output');
+    //anElement.innerHTML += theText + "<br>";
+    console.warn(theText);
+  },
+  canvas: (function() {
+    var aCanvas = document.getElementById('occViewerCanvas');
+    var aGlCtx =                   aCanvas.getContext ('webgl2', { alpha: false, depth: true, antialias: false, preserveDrawingBuffer: true } );
+    if (aGlCtx == null) { aGlCtx = aCanvas.getContext ('webgl',  { alpha: false, depth: true, antialias: false, preserveDrawingBuffer: true } ); }
+    return aCanvas;
+  })(),
+
+  onRuntimeInitialized: function() {
+    //console.log(" @@ onRuntimeInitialized()" + Object.getOwnPropertyNames(OccViewerModule));
+  }
+};
+
+const OccViewerModuleInitialized = createOccViewerModule(OccViewerModule);
+OccViewerModuleInitialized.then(function(Module) {
+  //OccViewerModule.setCubemapBackground ("cubemap.jpg");
+  OccViewerModule.openFromUrl ("ball", "samples/Ball.brep");
+});