A few python3 fixes.

- Fix one implicit relative import.
- Fix call to file builtin in test_env.
- Fix deprecated lambda syntax.

pubs/p3.py

@@ -12,12 +12,14 @@ else:
     import configparser
     ustr = str
     uchr = chr
+    file = None
     from urllib.parse import urlparse
     from urllib.request import urlopen
     from http.client import HTTPConnection
 
 configparser = configparser
 input = input
+file = file
 
 
 def isbasestr(obj):

pubs/templates/__init__.py

@@ -1 +1 @@
-from str_templates import *
+from . str_templates import *