OpenGl_Context now skips loading functions related to mapping buffer,
which are required by OpenGL ES 3.0 specs but not provided by WebGL 2.0.
Message_PrinterSystemLog does not use a broken emscripten_log() anymore, which corrupted UNICODE strings.
WasmOcctView::initWindow() - callbacks now set using EMSCRIPTEN_EVENT_TARGET_WINDOW
instead of 0 used by older Emscripten API.
Mouse callbacks now track canvas element and use
EmscriptenMouseEvent::targetX/targetY instead of ::canvasX/canvasY
as the latter was broken.
Added emscripten_set_main_loop() setup to shut up eglSwapInterval() error message.
Fixed missing \0 at the end of string converted by toUtf8Array().
The argument putEndl has been removed from Message_Messenger::Send() and Message_Printer::Send() methods.
Message_Printer interface has been changed, so that sub-classes have to implement new method
Message_Printer::send() accepting TCollection_AsciiString.
Old three Message_Printer::Send() methods remain available without putEndl argument
and redirecting to new send() method by default.
Removed dummy Message_PrinterOStream::GetUseUtf8() property.
Message_PrinterOStream, Message_PrinterSystemLog and Draw_Printer
now implement single method Message_Printer::send() instead of triplet.
Message_PrinterOStream::SetConsoleTextColor() skips color tags in case of Emscripten.
Message_PrinterSystemLog now implements log via emscripten_log().
