0.13.0

Removed:

• The xonsh code-base is no longer amalgamated, so tracebacks should be
  human-readable without intervention. This may have (minor) impacts on startup
  speed.

Fixed:

• Fix xontrib loading for free_cwd
• Fixed whole_word_jumping xontrib failing on Linux, conditional import of ptk_win32 → Windows only
• Fixed error caused by unintialized Xonsh session env when using Xonsh as a library just for its Pygments lexer plugin.

Authors:

• Gil Forsyth
• Noortheen Raja
• anki-code
• Eddie Peters
• cmidkiff87
• Hannes Römer