implement event selection with tokeninput, add title
add initial support for segment creation

TODO: handle selected segments
add better list formatting for segment labels
change insight caption based on selected segments
fix missing import
implement trends calculation and comparison by segment
calculate new cohort segment based on selected segment
fix typo in segment creation
pass original model to daily_users when creating segment
include selected segment label in cohort segment label
disable segment creation when comparing two segments
set colors for segment comparison series
fix date range
update readme and usage instructions
update preview.png
Merge pull request #4 from jtuulos/master

add interaction features and instructions