Fix B#21

Author: ToxicFrog

vstruct/io/i.lua

@@ -24,6 +24,8 @@ function i.unpackbits(bit, width)
 end
 
 function i.pack(_, data, width)
+  data = math.trunc(data)
+  
   if data < 0 then
     data = data + 2^(width*8)
   end

vstruct/io/u.lua

@@ -32,6 +32,7 @@ end
 function u.pack(_, data, width)
   local s = ""
   local e = io("endianness", "get")
+  data = math.trunc(data)
 
   for i=1,width do
     if e == "big" then