Added preliminary support for the SDL2 touch api. Missing items:
  1. Timestamps
  2. TouchID (the Device ID)
      As inline with the SDL spec, we will pass a touch ID of
      `SDL_TOUCH_MOUSEID` for touch events that are simulated by the
      mouse so games can rely solely on touch events if they like.

Includes the SDL2 Copyright notice on the headers that contain SDL2
content.
Includes a fix to SDL_PeepEvents.
Apply kripken's code formatting review to michaeljbishop's SDL2 touch pull request.
Implement SDL2 touch event timestamps and add a digital 0/1 pressure if no pressure data is present.
embind doesn't always need the full std::type_info record.  if EMSCRIPTEN_HAS_UNBOUND_TYPE_NAMES=0, then use a lighter type identifier.  This shaves 175 KB off of our engine's minified JavaScript.
Add a way to opt out of compiler-generated type names for smart pointers and wrapper types.
Always require an explicit name for shared_ptr and wrapper type bindings
some compile fixes
Add interactive and automated testing for SDL touch events.
Remove undefined behavior reading 32-bit variables as 64-bit in printf formatting in test_atomic_cxx. Fixes the test on OSX.
Allow setting SPIDERMONKEY_ENGINE=None in .emscripten to simplify test runner operation.
Store CMAKE_AR and CMAKE_RANLIB in CMake CACHE so that the values persist to user CMake toolchain files. Also CACHE the variable Emscripten, in the hope of that fixing the visibility issue with variable. Some users have reported that in their CMakeLists.txt files the variable EMSCRIPTEN is not always visible, even though in the Emscripten cmake unit tests it always works. Fixes #2288. Thanks mhenschel!
Merge pull request #2290 from juj/fix_test_atomic_cxx

fix_test_atomic_cxx
Merge pull request #2291 from juj/spidermonkey_none

spidermonkey_none
Merge pull request #2286 from chadaustin/embind-code-size-reduction

Embind code size reduction by using lightweight RTTI record for non-polymorphic types
Merge pull request #2285 from juj/sdl2-touch-api-additions

Sdl2 touch api additions
1.15.1
Fix browser.test_sdl_touch to pass touch coordinates inside the canvas rectangle.
stop using __proto__ as an optimization, it actually makes things slower
1.16.0