Fix for regexp limit search

Hey,

don't know if this is useful or by any means good - I've put a slow but works fix in for when you search with a regexp and a limit #6 - it applies the limit in the filter step when a regexp and limit is detected.

Also I've added 2 tests based on @juliangruber 's gists for #5 and #6:

#5 (end event + regexp) https://gist.github.com/juliangruber/7180395
#6 (limit + regexp) https://gist.github.com/juliangruber/7180416