Remove unused imports and fix some other linter errors.

recipe_engine/doc.py

 #!/usr/bin/env python
 # Copyright 2013 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 from __future__ import print_function
 
 import collections
 import inspect
 import os
 import sys
 
 from . import loader
 from . import run as recipe_run
-from . import package
 from . import recipe_api
 
 def trim_doc(docstring):
   """From PEP 257"""
   if not docstring:
     return ''
   # Convert tabs to spaces (following the normal Python rules)
   # and split into a list of lines:
   lines = docstring.expandtabs().splitlines()
   # Determine minimum indentation (first line doesn't count):
@@ skipping 94 matching lines @@
       p(1, 'behaves like %s' % map_to_cool_name(cool_base))
 
     if mod.API.__doc__:
       for line in trim_doc(mod.API.__doc__):
         p(2, '"', line)
 
     for fn_name, obj in member_iter(subinst):
       if fn_name in base_fns:
         continue
       pmethod(1, fn_name, obj)