SpigotMC#3622: Revert "SpigotMC#3256: Allow - and . in online mode as…

… some accounts still have these…"

This reverts commit f4f94d3.

proxy/src/main/java/net/md_5/bungee/util/AllowedCharacters.java

@@ -17,7 +17,7 @@ private static boolean isNameAllowedCharacter(char c, boolean onlineMode)
     {
         if ( onlineMode )
         {
-            return ( c >= 'a' && c <= 'z' ) || ( c >= '0' && c <= '9' ) || ( c >= 'A' && c <= 'Z' ) || c == '_' || c == '.' || c == '-';
+            return ( c >= 'a' && c <= 'z' ) || ( c >= '0' && c <= '9' ) || ( c >= 'A' && c <= 'Z' ) || c == '_';
         } else
         {
             // Don't allow spaces, Yaml config doesn't support them