Perform automatic migration to Python 3.x

Use lib2to3 automatic migration tool provided by Python 2.x to convert
codebase to new idioms.

Command line:

find . -type f -name '*.py' \
    -exec python2.7 -m lib2to3 \
    -f all -f idioms -f buffer -f set_literal -f ws_comma -w \
    '{}' '+'

@@ -102,3 +103,3 @@
 # adds a key and ensures it has the given email address
 def add_key( keyhome, content ):
-	p = subprocess.Popen( build_command(keyhome, '--import', '--batch'), stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE )
+	p = subprocess.Popen( ['/usr/bin/gpg', '--homedir', keyhome, '--import', '--batch'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE )

@@ -342,3 +342,3 @@
 
 	if gpg_to != list():
-		log("Encrypting email to: %s" % ' '.join( map(lambda x: x[0], gpg_to) ))
+		log("Encrypting email to: %s" % ' '.join( [x[0] for x in gpg_to] ))

@@ -597,3 +597,3 @@
 		address = address.lower()
 	else:
-		splitted_address = address.split('@')
+		if isinstance(address, str):

@@ -95,0 +101,4 @@
+                 config.get("relay", "script"),
+                 config.get("relay", "port")]
+
+    logging.debug("Spawning relay: '%s'" % (relay_cmd))

@@ -95,3 +95,3 @@
 
 	for to in recipients:
-		if to in keys.values() and not get_bool_from_cfg('default', 'dec_keymap_only', 'yes'):
+		if to in list(keys.values()) and not get_bool_from_cfg('default', 'dec_keymap_only', 'yes'):