Sending an email that generates a Log does not remove all HTML characters from Log notes

When sending an Email that generates a Log (e.g., from the "Send Email" action on the Accounts form) and the email is formatted as HTML, the Log Notes for the Log that is generated are automatically set to be the Email content with the HTML tags removed.

However, HTML can also consist of entities, e.g., the non-breaking space attribute. These always begin with an ampersand and end in a semi-colon. These were not being stripped out, and were therefore being included in the Log Notes.

The ISRuntime, ISHtmlUtilities.PlainTextFromHtml function has been updated to remove entities as well as HTML tags.