libs/common: remove deprecated PanicXXX functions (#3595)

* Remove deprecated PanicXXX functions from codebase

As per discussion over
[here](https://github.com/tendermint/tendermint/pull/3456#discussion_r278423492),
we need to remove these `PanicXXX` functions and eliminate our
dependence on them. In this PR, each and every `PanicXXX` function call
is replaced with a simple `panic` call.

* add a changelog entry

libs/common/random.go

@@ -300,7 +300,7 @@ func cRandBytes(numBytes int) []byte {
 	b := make([]byte, numBytes)
 	_, err := crand.Read(b)
 	if err != nil {
-		PanicCrisis(err)
+		panic(err)
 	}
 	return b
 }