Added BlackBerry support

Added BlackBerry support
Fixed bug where fgPlatformSetWindow (for EGL) could be called with window being NULL.
Related, the function does nothing if the window is the current window
Updated fghPlatformCloseWindowEGL so that it mimics the Windows function:
- If the current window is getting destroyed, then reset eglMakeCurrent to "null" values
- Iterate through windows to make sure a EGL context isn't being shared between other windows before destroying it