MathShadow is now drawn correctly

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Made the default size of MathObject a static variable.

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Fixed the parentheses for powers

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>