TODO:

* What are filters?
* List+explain all existing filters (pongo2 + pongo2-addons)

Implemented filters so far which needs documentation:

* escape
* safe
* escapejs
* add
* addslashes
* capfirst
* center
* cut
* date
* default
* default_if_none
* divisibleby
* first
* floatformat
* get_digit
* iriencode
* join
* last
* length
* length_is
* linebreaks
* linebreaksbr
* linenumbers
* ljust
* lower
* make_list
* phone2numeric
* pluralize
* random
* removetags
* rjust
* slice
* stringformat
* striptags
* time
* title
* truncatechars
* truncatechars_html
* truncatewords
* truncatewords_html
* upper
* urlencode
* urlize
* urlizetrunc
* wordcount
* wordwrap
* yesno

* filesizeformat*
* slugify*
* truncatesentences*
* truncatesentences_html*
* markdown*
* intcomma*
* ordinal*
* naturalday*
* timesince*
* timeuntil*
* naturaltime*

Filters marked with * are available through [pongo2-addons](https://github.com/flosch/pongo2-addons).