Fix for Chat in PUN PLUS v1.58

In v1.58 of the PUN package, Chat won't work on almost any platform. The cause for that is that a compile condition define went missing in the source. You can add that easily.

In ChatPeer.cs, a define is missing. Add this right below the file-comment block:

#if UNITY_3_5 || UNITY_4 || UNITY_4_1 || UNITY_4_2 || UNITY_4_3 || UNITY_4_4 || UNITY_4_5 || UNITY_4_6 || UNITY_5 || UNITY_5_0 #define UNITY #endif

With that, UNITY is defined and the code can select a fitting socket implementation.

Another issue that might happen: Unity does not always detect correctly that a network connection is required.
In the Player Settings, "Other Settings", make sure Internet Access is set to "Require".