Release v0.1.6 (Roaring 20s)

This release features some bug fixes and new features:

• A new trace option to record the database instance name, called WithInstanceName.
  This feature is useful to differentiate between different database names. It was requested by
  @vearutop in issue #33 and then resolved by PR #34
  It can be used when creating a driver like this

driverName, err = ocsql.Register("mysql", ocsql.WithAllTraceOptions(), ocsql.WithInstanceName("prod8"))

• A bug fix to correctly catch and record errors produced, and propagate them when tracking latency.
  The cause of the issue was in our defers we were directly getting a closure and passing err directly into it
  which would use the earliest value of the named error value err e.g.

func foo() (err error) {
     defer tracker(...)(err)
     ....

but really what we wanted was

func foo() (err error) {
     onDeferFn := tracker(...)
     defer func() {
          onDeferFn(err)
     }()
     ....

This bug was noticed and fixed by @otternq in PR #43.

Thank you everyone for all the changes, bug reports and fixes and for the reviews!