Move widont filter to applyfilters function

[barrysteyn]

The Pelican project has the ability to use the ignoretags feature via its settings (I added that feature). The only thing that is not ignored is the widont filter, which I get a high quantity of queries asking me to do. Here is one example: H1 should always be ignored by typogrify (including widont) by certain parts of the HTML template.

Also, there is a need to be able to have a switch that will turn certain filters off. Having all filters in one function will allow this functionality to be easily added