Links to Intersoft website now use HTTPS

Several links to the Intersoft website, e.g., from the bottom of the login form, were sill using HTTP.

The following links have been updated to use HTTPS:
* The bottom of the login form
* The bottom of the forgotten password form
* The bottom of the password reset form
* The bottom of the login form for the Administration facility

NOTE: These links also have the rel="noreferrer" attribute added so that Google Lighthouse does not flag them.

Other links that have been upgraded to use HTTPS include:
* A link to Google fonts in a CSS file