update build settings - specify OS 10.7 SDK everywhere
Fix bugs in mailimap_date_time_send
 - entire string must be quoted
 - timezone must be preceded by "+" or "-" as appropriate (not always a "+"!)
Use sprintf() to format the string, rather than multiple individual "mailimap_char_send" (etc.) calls
   (makes it much easier to see what the formatted string actually looks like)