Draft: Some HUD changes

Exactly what the title says, and the changes are:

• HU_drawPing has a new blue color if your ping is lower than 76ms.
• Ping counter flashes red when its higher than 400ms.
• Unrelated, but playerpingtable is exposed as player.ping
• Input no longer being restricted to record attack, with a new showinput cvar.

Since i am completely new on making merge requests, please tell me some issue that you find!