v1.2.0

• Add get() and getall() methods as aliases for extract_first and extract respectively
• Add default value parameter to SelectorList.re_first method
• Add Selector.re_first method
• Bug fix: detect None result from lxml parsing and fallback with an empty document
• Rearrange XML/HTML examples in the selectors usage docs
• Travis CI:
  • Test against Python 3.6
  • Test against PyPy using "Portable PyPy for Linux" distribution