Add support for stats command

[SteveBox0]

Stats command provides useful information such as server FPS

[galexrt]

@SteveBox0 do you have a sample stats command output (+ game name)?

[SteveBox0]

Here is an example for CSGO but from my understanding is the same for all source games.

   CPU   NetIn   NetOut    Uptime  Maps   FPS   Players  Svms    +-ms   ~tick
   0.0      0.0      0.0      24     0  125.31       0    0.26    0.38    0.21