Don't capture control-tab events.

It's annoying not to be able to tab away from the page!
Refactor to reduce nesting
Declare function-local variables properly

Variables inside if-clauses are indeed hoisted to the top of the
enclosing scope. It's bad form to make `var` declarations inside an
if-clause.

sel is now function-local, rather than global :(
 Merge branch 'tab-modifiers' into 'master'

Don't capture control-tab

Allows tabbing away from hastebin