xonsh 0.6.3

on Python PyPI

Added:

• Docs for using @(<expr>) as a way to run commands and a gotcha about
  list of strings vs single string expressions.
• Ubuntu versions which xonsh is packaged for (with xonsh versions)

Changed:

• When reporting errors without a traceback (i.e. $XONSH_SHOW_TRACEBACK = False) and the error is a XonshError
  the exception type is not longer printed.
• CommandPipeline.proc may now be None, to accomodate when the process
  fails to even start (i.e. a missing command or incorrect permisions).

Fixed:

• The curl command will now be run in a thread, which prevents documents that
  do not end in a newline from writing over the next prompt and vice versa.
• Fix bug on Windows when PATHEXT environment variable did not exist.
  This also fixes building the xonsh documentation on Windows.
• Fixed a bug in the free_cwd <http://xon.sh/xontribs.html#free-cwd>__ Windows Xontrib, which caused the prompt to error if the current directory is
  deleted/renamed from an other process.
• Fixed issue with $XONSH_SHOW_TRACEBACK not being respected in subprocess
  mode when the command could not be found or had incorrect permissions.