Paragraph positioning only determined by end of line marker, not P or BR tags

Issue Summary

Problem/Motivation

I opened this issue a while back wondering why my embedded ads weren't working with WYSIWYG, and found a configuration change that made them start working, but on further consideration, I have a lot of sites that have using a WYSIWYG editor for a while, and have a bunch of old content without any line breaks. I think the ad_embed module should be smart enough to also check for P (and maybe BR) tags as well.

Proposed resolution

We need the paragraph "counter" to be a little smarter, and also check for HTML paragraph breaks.