* fix some syntax and 3k issues for py/path and py/process, tests only partially working

* have py.process.cmdexec return unicode/text (for now)
* rename py.builtin.basestring to _basestring

--HG--
branch : trunk

py/code/source.py

@@ -25,7 +25,7 @@ class Source(object):
                 partlines = []
             if isinstance(part, Source):
                 partlines = part.lines
-            elif isinstance(part, py.builtin.basestring):
+            elif isinstance(part, py.builtin._basestring):
                 partlines = part.split('\n')
                 if rstrip:
                     while partlines: