Fix arguments handling

Now all arguments are parsed. A non-valid argument will exit the program with an error.

kvmstats/kvmstats

@@ -19,7 +19,7 @@ done
 
 POW=$(echo 1024 ^ 3 | bc)
 FMT=human
-while [ $# -ne 0 ] && echo "$1" | grep -q '^-[[:alnum:]]'
+while [ $# -ne 0 ]
 do
     case $1 in
     '-a')
@@ -40,6 +40,7 @@ do
             usage
             ;;
         esac
+        shift
         ;;
     '-u')
         case $2 in
@@ -55,6 +56,7 @@ do
         *)
             usage
         esac
+        shift
         ;;
     *)
         usage