In RGSS, uninitialized disposable objects (and Fonts, sort of) are technically disposed, and other objects (Tone, Color, Rect, and Table) are created with all values set to 0. It's also possible to reinitialize them, although reinitializing disposables leaks memory.
This commit causes MiniFFI and FileInt objects to improperly raise disposed errors if used while uninitialized, but that feels acceptable to me.
It's currently not (much of) a problem because few or no games use multiple threads, but I believe that ruby can run its garbage collector while the GVL is released, which means that Graphics.update and Graphics.wait are currently not thread safe.
Moving the call to GFX_LOCK into dispose() should fix this.
+ Time is now measured in fractions of a second, not microseconds
+ Viewports in RGSS1 will now only retain weak references to their children
+ Invalid Sprite bitmaps found during Graphics.update will be treated as null
+ Bitmap#mega? and Bitmap#animated? are properly rescued
