Code review comment for lp:~epics-core/epics-base/link-support-2

Done what I think are my final commits, moving code out of readLocked(), fixing issues and adding tests.

I also added a feature to the subArray record, which can now be used as a lookup table, and fixed a bug in the event record.

I think I'm going to close this merge request and open up a new one for the git repo, to make it easier to examine the diffs against the current Base-3.16.