* clist: Speedup detachNext() and detachPrev()
We used unnecessary function calls, defers, and extra mutexes.
These are not our friends for writing fast code in our libs.
* Remove more defers from clist functions
* Add more benchmarks
This commit switches all usage of math/rand to cmn's rand. The only
exceptions are within the random file itself, the tools package, and the
crypto package. In tools you don't want it to lock between the go-routines.
The crypto package doesn't use it so the crypto package have no other
dependencies within tendermint/tendermint for easier portability.
Crypto/rand usage is unadjusted.
Closes#1343
