Show OTR coloured status

Customisable within theme files e.g.:
titlebar.unencrypted=red
titlebar.encrypted=green
titlebar.trusted=red
titlebar.untrusted=green

Shows [unencrypted] for all non-OTR chat

Disable with '/otr warn off'

src/config/preferences.h

@@ -58,7 +58,8 @@ typedef enum {
     PREF_AUTOAWAY_MODE,
     PREF_AUTOAWAY_MESSAGE,
     PREF_CONNECT_ACCOUNT,
-    PREF_OTR_LOG
+    PREF_OTR_LOG,
+    PREF_OTR_WARN
 } preference_t;
 
 void prefs_load(void);