automatically copy Registrar #s from Sites to Catalogue module

[ljwalker]

What module(s) and tab(s) would this change affect?
Catalogue: Invert. Paleo. tab, Registrar tab & Sites: Station Data tab

Is your request related to a problem? Please describe.
IP would prefer that registrar-related numbers stored in the Sites module be automatically copied to new Catalogue records to prevent omission and copy-paste issues.

Describe the solution you'd like
When a new Catalogue record is created and then a Sites record is attached, the values in Accn. No. on the Sites module should automatically copy over to Accn. No. and Registrar Number in the Catalogue module.

Additional context
Note that this information in the Sites module is currently on the Station Data tab, but as per GitHub Issue #54 , this field will eventually move to the Sites module: Invert. Paleo. (1) tab and become Registrar No.

In the Catalogue module, Accn. No. would then become read-only.

[ljwalker]

As part of this request, the contents of Registrar No. will be inserted in the summary lines on the Catalogue and Sites modules, to be semicolon delimited: