Remove all trailing whitespaces in the code tree

Just run:
````
 $ find -name '*.c' -print0 | xargs -r0 sed -e 's/[[:blank:]]\+$//' -i
 $ find -name '*.h' -print0 | xargs -r0 sed -e 's/[[:blank:]]\+$//' -i
````

Trivial, but useful