Parentheses examples makes more sense

In the old example, parentheses had no impact because multiplication should have precedence over addition.

Thanks to @inseo for the suggestion.
Merge pull request #770 from kaelig/patch-1

Parentheses example make more sense
Use sass_warn for @debug.

Closes #775
Escape "*/" in full exceptions.

Closes #778
Preserve the bang in /*! comments.
Merge remote-tracking branch 'origin/stable' into stable
Update INDENTED_SYNTAX.md

fix a typo
Merge pull request #802 from lkdjiin/patch-1

Update INDENTED_SYNTAX.md
Fix an @extend trimming bug.

Closes #788.
Merge remote-tracking branch 'origin/stable' into stable