Replace Gwen::Event::Packet with void*

[garrynewman]

Replace Gwen::Event::Packet with void*

[jswigart]

This was not a good change. You could have added a void* to the packet structure but replacing packet entirely with void* loses built in type safety and multi field ability of the user data for basic types, not to mention leaks memory for anything you allocate for the user data. I can understand the need to put more complex information in the packet than the types supported, but the fix for that isn't replacing it with void *. At a minimum you could add a void * to the packet. Even better, a little template wrapper could provide a type safe and memory leak safe wrapper around whatever pointer you allocate for the data.

[Wizzard033]

This is the way other libraries do it so I just emulated them.

I'm sure there is a better way.

EDIT: Also, there is no memory leak here except for when people use it wrong.
You have to allocate the data the void pointer points to with new and later delete it.