Fix wrong imports

- "from _compatibility import ..." (not in circular imports)
- "from jedi import builtin" (one of circular imports)
- "api_classes = api.api_classes"
  ("from jedi import api_classes" is not supported)

jedi/evaluate.py

@@ -68,11 +68,11 @@ backtracking algorithm.
 
 .. todo:: nonlocal statement, needed or can be ignored? (py3k)
 """
-from _compatibility import next, hasattr, is_py3k, unicode, reraise
 
 import sys
 import itertools
 
+from jedi._compatibility import next, hasattr, is_py3k, unicode, reraise
 from jedi import common
 from jedi import cache
 from jedi import parsing_representation as pr