add RGSS 3.0.1 etc classes equality comparison

RGSS 3.0.1 finally fixed #==, #===, #eql? for Color, Tone, and Rect.
Now instances of them can be compared to other kinds of objects.
bump RGSS_VERSION to 3.0.1
Merge pull request #67 from cremno/add-rgss-3-0-1-etc-classes-equality-comparison

add RGSS 3.0.1 etc classes equality comparison