Add feature straighten by x degrees (45 for e.g)

changes straighten(), fxStraighten(), straightenObject() and  fxStraightenObject() function to allow passing an Int param that is used to define angle steps

for e.g straighten(45) would allow following angle steps 0, 45, 90, 135, 180, 225, 270, etc.

passing no param default to 90.

Let me know if this can be usefull to you and / or if i should improve the way i did it.

Thanks.