Add vCard support

Only nicknames, photos, birthdays, addresses, telephone numbers, emails,
JIDs, titles, roles, notes, and URLs are supported

Due to the synopsis array not having enough space, `/vcard photo
open-self` and `/vcard photo save-self` are not documented properly in
the synopsis section of the `/vcard` command, but they are documented in
the arguments section

Fixed memory leak in vcard autocomplete (thanks to debXwoody)

src/config/preferences.h

@@ -105,6 +105,7 @@ typedef enum {
     PREF_TIME_XMLCONSOLE,
     PREF_TIME_STATUSBAR,
     PREF_TIME_LASTACTIVITY,
+    PREF_TIME_VCARD,
     PREF_STATUSES,
     PREF_STATUSES_CONSOLE,
     PREF_STATUSES_CHAT,
@@ -181,6 +182,7 @@ typedef enum {
     PREF_NOTIFY_ROOM_OFFLINE,
     PREF_OX_LOG,
     PREF_MOOD,
+    PREF_VCARD_PHOTO_CMD,
 } preference_t;
 
 typedef struct prof_alias_t