Blender Git Loki

Really minor updates related to code I wrote for the Cast modifier:

- modifier.c: moved a check out of a loop, removed an unneeded var, made a couple cosmetic changes.

- DNA_modifier_types.h: added parentheses to cast and smooth modifier defines that used bit-shifting (like 1<<1, etc.).

Note: realized they were needed when I tried to use "flag &= ~MOD_CAST_Z" in modifier.c. Since MOD_CAST_Z is #defined as 1<<3, ~MOD_CAST_Z ended up as ~1<<3 while I wanted ~(1<<3). There are other places in that header file and others in Blender where it'd be safer to add the parentheses...

- Updated the epydoc documentation for the features added by Ben Batt to the cast modifier; fixed small typo in API_intro.py.

BTW, thanks Ben Batt (artificer) for checking, improving with a couple features and committing these modifiers :).