Decode HTML entities in iCalendar text

[jensschuppe]

Overview

Fixes dev/core#1541 (and the much older https://issues.civicrm.org/jira/browse/CRM-13645). iCal event description contains encoded HTML entities when it should be plain text. This PR decodes HTML entities.

Before

Text in iCalendar file contains HTML entities like ü or &npsp;.

After

HTML entites are decoded to plain text.

Technical Details

Note from user pminf:

Note that html in iCalendar is fine if the "Alternate Text Representation" points to a "text/html" content portion (see https://tools.ietf.org/html/rfc5545#section-3.2.1 for details).

Comments

This is basically just the patch that had been provided in the issue by user pminf.

[civibot]

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[mlutfy]

hi @jensschuppe - thanks for the patch!

I stumbled on this bug as well, and the PR fixes a large part of the problem. I also had another issue, because of the str_split, but I will open a separate PR.