differentiate control frame and data frame

Merge pull request #92 from zachzhaozy/add-function-closechan-for-ses…

v1.5.16

fix shaper prio overflow

bug fix for https://github.com/xtaci/smux/issues/82

trigger waitRead to return in SetReadDeadline

OpenStream should return false if read has error issue#61

fix a possible race condition

fix a possible race condition

expose errors definition in smux