Add FFT, Fixes #16

[Vurv78]

• Changed wa_think interval to 100ms.
• Added GetFFTEnabled (SHARED), SetFFTEnabled (SERVER)
• Added GetFFT (SHARED, but really SERVER)
• Added getFFT, getFFTEnabled, setFFTEnabled for E2
• Docs on readme, e2helper, steam readme

[Vurv78]

Prob want a convar though since even if it takes barely any net server owners might not like the constant net usage