Context Navigation

Changes between Version 1 and Version 2 of Ticket #6772, comment 40

v1	v2
9	9	- In order for links to work while using `<iframe sandbox>`, I had to add the `sandbox="allow-top-navigation"` attribute. The other gotcha here is in order for links to be clickable, links must use `top.location.href`. (See `bp_activity_embed_excerpt_onclick_location_filter()`.) If we'd rather links open in a new window, let me know.
10	10	- Uses a template part to output the inline CSS (see `/embeds/activity/css-activity.php`). In order to auto-generate the RTL CSS, I'm piggybacking off of `grunt rtlcss` to generate the related RTL CSS template part. As to why I'm opting for inline CSS, see comment:36.
	11	- Removes inline images from being displayed if no oEmbed item is found. Reason why I removed it is `<img src>` could potentially be vulnerable. Maybe I'm being too cautious here. Let me know if we should reinstate this.
11	12
12	13	Here's a screenshot of a TED video in action: