libsass: updated to 3.6.2

3.6.2:
Improve pseudo selector handling
Code improvements
Fix various functions arguments
Fix "call" for $function
Check weight argument on invert call
Improve makefile to use dylib extension on MacOS
Fix bug in scale-color with positive saturation
Minor API documentation improvements
Fix selector isInvisible logic
Fix evaluation of unary expressions in loops
Fix attribute selector equality with modifiers

(adam)