New/improved iocsh debug utility functions

[Dirk Zimoch <dirk.zimoch@psi.ch>]

Hello,

I had written/modified some iocsh debug utility functions I would like 
to share. I would like to share them and wonder which branch to make the 
merge request against.

I have originally developed them for 3.14 and some tiny modifications 
are necessary for newer EPICS versions. How to handle that? Make 
separate merge requests for 3.14, 3.15, 3.16 and 7? Or only a sub-set?
Or can I somehow combine all changes into one merge request?

These are the shell functions:

dbla (list aliases)
Improvement: Instead of only finding the real record names for given 
aliases, also find the alias names of given real record names.

dbll (list links)
New: List all database links to given records or fields.

dbli (list info)
New: List all info fields matching given naming patterns.

cal (channel access list)
New: List all channel access connections to given records or fields.

Feedback welcome.
Dirk