Make sharecodes platform-independent

Resolves the issue of sharecodes generated with the 32-bit version
of LÖVE being incompatible with the 64-bit version, and vice versa.

This also happens to shorten the sharecodes by removing all of the
"A"s at the beginning. :)

src/randomizer.lua

@@ -399,7 +399,7 @@ function C:_updateSharecode(seed)
     seed = seed .. (" "):rep(20-#seed)
   end
 
-  local packed = love.data.pack("data", "sBB", seed, settings, seq)
+  local packed = love.data.pack("data", "<s1BB", seed, settings, seq)
   self.sharecode = love.data.encode("string", "base64", packed)
 
   logNotice(("Sharecode: %s"):format(self.sharecode))

src/ui/draw.lua

@@ -269,7 +269,7 @@ end)
 settings.importshare:onPress(function()
   local success, seed, sharesettings, seq = pcall(function()
     local packed = love.data.decode("data", "base64", settings.sharecode.value)
-    local seed, settings, seq = love.data.unpack("sBB", packed)
+    local seed, settings, seq = love.data.unpack("<s1BB", packed)
     assert(#seed == 20)
     return seed, settings, seq
   end)