Update usage and mention required lua version

README.md

@@ -2,14 +2,17 @@
 
 ## Requirements
 
-* lua
+* lua >= 5.3
 * curl
 * sed
 * date
 
 ## Usage
 
-    c4mate [-u <user>] [ <query> | -b <id> | -l | +/-<amount> | -g <amount> <user> [<reason>]]
+If no username is given via the "-u" command line flag, c4mate will use the
+value of the $USER environment variable as username.
+
+    Usage: c4mate [-u <user>] [ <query> | -b <id> | -l | +/-<amount> | -g <amount> <user> [<reason>]]
     Display current balance:
         c4mate
     Find and buy item (interactive):

c4mate

@@ -189,8 +189,8 @@ function MatePad:print_log(log)
         event = log[i]
         if event.method == "buy" or event.method == "recharge" then
             print(string.format(
-                "[%s] Bought %s",
-                event.time, event.name
+                "[%s] Bought %s (#%d)",
+                event.time, event.name, event.parameter
             ))
         elseif event.method == "set_balance" then
             print(string.format(