Several fns with doc string in wrong place

[jafingerhut]

These functions have their doc strings after the arg lists, but they should be before the arg list:

seesaw.graphics/to-stroke
seesaw.layout/handle-structure-change
seesaw.selector/class-of
seesaw.util/
to-seq
boolean?
atom?
try-cast
to-url
to-uri