optimize AES decryption time
from 1.8Mb/s to 3.6Mb/s on Core-i5 2410M @2.30 GHz
the bottleneck was the timer not restarting quickly.
to workaround this, we continue to decrypt chunk of data until we reach a duration of 20ms.
related to https://github.com/mangui/HLSprovider/issues/55
optimize AES decryption

from 3.6 Mb/s to 4.8 Mb/s on Core-i5 2410M @2.30 GHz
use updated as3crypto.swc from https://github.com/mangui/as3-crypto
I optimize AES decryption, using fastmem.as from http://www.buraks.com/azoth
related to https://github.com/mangui/HLSprovider/issues/55