Refactor email templates

theme/templates/email/trades/trade_update_thanked_by_both.txt

@@ -0,0 +1,14 @@
+{% include 'email/common/header.txt' %}
+
+{{ acting_user }} ({{ acting_user_friend_code }}) has sent their thanks for the successful trade!
+
+Trade Details:
+- {% if is_initiator %}They sent: {{ has_card }}{% else %}You sent: {{ want_card }}{% endif %}
+- {% if is_initiator %}They received: {{ want_card }}{% else %}You received: {{ has_card }}{% endif %}
+(#{{ hash }})
+
+This trade is now completed; no further actions can be made.
+
+Thank you for using PKMN Trade Club.
+
+{% include 'email/common/footer.txt' %}