move ffs parser source code into new `misc` directory
ffs/wizard code into own module
reorganize, add explaination
more verbose query building

includes inline comments for individual query parts and some
general annotations of the different sections as well as the
whole query
use relative dates for newer:* searches
relative dates are in the past by default

this makes the following query read almost naturally:

  <newer than="{{date:3 days}}"/>
Merge branch 'master' into ffs
add tests for ffs module