libsass 0.6.0

Note that since libsass-python 0.6.0 (and libsass 3.0) it requires C++11 to compile. Although 0.6.2 became back to only need GCC (G++) 4.3+, LLVM Clang 2.9+, from 0.6.0 to 0.6.1 you need GCC (G++) 4.8+, LLVM Clang 3.3+, or Visual Studio 2013+.

• Follow up the libsass upstream: 3.0 — See the release note of Libsass.
  • Decent extends support
  • Basic Sass Maps Support
  • Better UTF-8 Support
  • call() function
  • Better Windows Support
  • Spec Enhancements
• Added missing partial import support. [#27 by @item4]
• SOURCE_COMMENTS became deprecated.
• sass.compile()'s parameter source_comments now can take only bool instead of str. String values like 'none', 'line_numbers', and 'map' become deprecated, and will be obsolete soon.
• build_directory() function has a new optional parameter output_style.
• :meth:Build.build() method has a new optional parameter output_style.
• Added --output-style/-s option to build_sass command. [#25]