Key changes:

• Added implementation for linux Application ::PrintCallStack ::CaptureCallStack and ::DumpCallStack .
• Added atomic_fixed_buffer and test for it.
• Added GPI_SURFACE_DESTROYED event to signal complete surface destroying.
• GPI_Surface on android now correctly resets its resources on context loss and sends GPI_SURFACE_RESET.
• Mutex refactored to remove uneeded class.
• Refactored ThreadStorage.
• Added spin_lock.
• Fixed not thread-safe window creation under windows[Issue:22].
• Fixed incorrect Folder::OpenFilePath behavior.
• Fixed reference counting in IPI devices.
• IPI_Gamepad for windows implementation (simple winmm).