Move SassScript parse nodes into Sass::Script::Tree.
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.
Rename Sass::Script::Literal to Value.
Move SassScript value classes to lib/sass/script/value.

Also rename Sass::Script::Value to Sass::Script::Value::Base.
Attach source range information to SassScript Lexer tokens.
Improve List#inspect
Clean up source range assignment in the SassScript parser.
Make sure Lexer returns the correct line/offset.
Fix a typo in an error message.
Add Literal classes to wrap Values in parse trees.
Remove Sass::Script::Value::Base from the Sass::Script::Tree::Node hierarchy.
Add redirects for the old Script names.
Don't print a warning for old Sass::Script constants for now.

After the next release, we'll add a warning; after the release after that, we'll
remove them.
Add a changelog entry about the script refactor.
Merge pull request #770 from kaelig/patch-1

Parentheses example make more sense
Don't strip bangs from loud comments (closes: #784)
Merge branch 'loud_comments' of https://github.com/superlukas/sass into superlukas-loud_comments

Conflicts:
	lib/sass/engine.rb
Merge branch 'superlukas-loud_comments'
Added Sass Function: unique-id()

Returns a unique CSS identifier within the scope of a single CSS file.
This is most useful for creating placeholder classes that can be
used within a runtime condition context E.g. @media or @supports.
Merge branch 'unique_id'

Conflicts:
	doc-src/SASS_CHANGELOG.md