add spec for blanking index on backspace
don't truncate in narrow windows (fixes #22)
blank the whole line before drawing

When the drawn text includes ANSI escape codes, we can get confused
about which column we're on. This patch changes from blanking after
drawing to blanking before.
reset index when deleting word
don't draw past bottom of short screen (fixes #26)
extract method: run_in_screen
fix failing specs; oops
Fix undefined local variable or method `search'
Merge pull request #27 from mavcunha/master

Fix undefined local variable or method `search'