console.lua: trim commands before saving them in history

This avoids storing similar commands in history that only differ by
leading or trailing whitespace, like "sub-reload" and "sub-reload ". It
is easy to get these otherwise because Tab completion leaves a trailing
space after commands.

player/lua/console.lua

@@ -796,6 +796,8 @@ local function handle_enter()
         return
     end
 
+    line = line:match('^%s*(.-)%s*$')
+
     if line == '' and input_caller == nil then
         return
     end