compiling with several clang flags enabled, MotionBlur was a couple minor problems

MotionBlurFilter

- using floating point based abs instead of integer based
- declare as static inline for function prototype declaration

For the floating point conversion, we could add in a nearbyintf, if we want integer rounding
fixing a few more clang warnings for UIView+MotionBlur

- floating point based methods instead of integer based abs (we could use nearbyintf if we want rounding)
- opacity is a float, some systems CGFloat is a double

- missing newline at bottom of file warning
Merge pull request #1 from piemonte/master

a few clang warning fixes