- optimization : small approximation bit shift used instead of * or / number for TPA, rates, dynP, dynD and expo curb
- optimization : SerialAvailable is called only once per port and per cycle in Serial
- small bug correction: a uint8_t cast is needed before % in SerialAvailable()

git-svn-id: http://multiwii.googlecode.com/svn/trunk/MultiWii_shared@1376 02679b44-d973-9852-f2fa-63770883b36c