Version 0.39-alpha

New features in this release:

• Remade the renderer so that all the graphics commands are executed immediately on the graphics thread
• The window is now centered on Linux
• The cursor is now hidden properly on macOS
• ARM (Raspbian) and x86 Linux code is now merged into a single code base
• Ouzel now uses exceptions for error handling
• Emscripten target now supports fullscreen
• Long filenames (longer than PATH_MAX) are now supported on Windows
• Update thread can now be forced to wait on v-sync instead of running continuously
• Resources can (and must) now be loaded and unloaded in bundles
• Touch events are now supported on macOS
• A bunch of other small fixes and improvements