Migration from python2 to python3

- Refactor setup.py for python3
- Refactor libs/ansi.py
- Update dialog.py from upstream
- Fix shebang in qubesbuilder.BuildLog and refactor

libs/ansi.py

@@ -1,7 +1,5 @@
-#!/usr/bin/python2 -O
+#!/usr/bin/python3 -O
 # -*- coding: utf-8 -*-
-
-
 import curses
 
 
@@ -14,22 +12,30 @@ def __init__(self):
             except curses.error:
                 return
 
-            self['black']     = curses.tparm(curses.tigetstr('setaf'), 0)
-            self['red']       = curses.tparm(curses.tigetstr('setaf'), 1)
-            self['green']     = curses.tparm(curses.tigetstr('setaf'), 2)
-            self['yellow']    = curses.tparm(curses.tigetstr('setaf'), 3)
-            self['blue']      = curses.tparm(curses.tigetstr('setaf'), 4)
-            self['magenta']   = curses.tparm(curses.tigetstr('setaf'), 5)
-            self['cyan']      = curses.tparm(curses.tigetstr('setaf'), 6)
-            self['white']     = curses.tparm(curses.tigetstr('setaf'), 7)
-
-            self['bold']      = curses.tigetstr('bold')
-            self['underline'] = curses.tigetstr('smul')
-            self['inverse']   = curses.tigetstr('smso')
-            self['normal']    = curses.tigetstr('sgr0')
+            self['black'] = curses.tparm(curses.tigetstr('setaf'), 0).decode(
+                'utf-8')
+            self['red'] = curses.tparm(curses.tigetstr('setaf'), 1).decode(
+                'utf-8')
+            self['green'] = curses.tparm(curses.tigetstr('setaf'), 2).decode(
+                'utf-8')
+            self['yellow'] = curses.tparm(curses.tigetstr('setaf'), 3).decode(
+                'utf-8')
+            self['blue'] = curses.tparm(curses.tigetstr('setaf'), 4).decode(
+                'utf-8')
+            self['magenta'] = curses.tparm(curses.tigetstr('setaf'), 5).decode(
+                'utf-8')
+            self['cyan'] = curses.tparm(curses.tigetstr('setaf'), 6).decode(
+                'utf-8')
+            self['white'] = curses.tparm(curses.tigetstr('setaf'), 7).decode(
+                'utf-8')
+
+            self['bold'] = curses.tigetstr('bold').decode('utf-8')
+            self['underline'] = curses.tigetstr('smul').decode('utf-8')
+            self['inverse'] = curses.tigetstr('smso').decode('utf-8')
+            self['normal'] = curses.tigetstr('sgr0').decode('utf-8')
 
     def __new__(cls, *p, **k):
-        if not '_instance' in cls.__dict__:
+        if '_instance' not in cls.__dict__:
             cls._instance = dict.__new__(cls, *p, **k)
         return cls._instance