Simplify _compat.py now that we only run on newer Pythons

- We have u'literals' so we don't need a _u() function.
  For the record the Emacs replacement regex was
  `_u(\(['"]\)\([^)]*\)\1) -> u\1\2\1`. Amazingly, I typed that right
  on the first try.

A few things were only used in one (test) file or function, so it was
better to keep the use, if any, local and out of the "public" api:

- We can use io.StringIO everywhere and it's fast. It was only
 imported in one file anyway.
- We can just import pickle. It was only imported in one file anyway.
- TEXT was only used in one test function, `type(u'')` is just as
 clear (especially since the usual name is `text_type`).
- reload was only used in one test function, so move the definition
 there.

1 files changed, 3 insertions, 4 deletions

diff --git a/src/zope/security/_definitions.py b/src/zope/security/_definitions.py
index a54d7a8..e4f3867 100644
--- a/src/zope/security/_definitions.py
+++ b/src/zope/security/_definitions.py
@@ -17,12 +17,11 @@ import threading
 import zope.interface
 
 from zope.security import interfaces
-from zope.security._compat import _u
 
 thread_local = threading.local()
 
 @zope.interface.provider(interfaces.IPrincipal)
 class system_user(object):
-    id = _u('zope.security.management.system_user')
-    title = _u('System')
-    description = _u('')
+    id = u'zope.security.management.system_user'
+    title = u'System'
+    description = u''