Revert "remember currently edited form at end of history; refactor to minimize use of state and improve readability"

This reverts commit 36f4b33ae1c803cbe5fd4627f08a73add6bf3547.
Revert "make sure keys work cross-platform"

This reverts commit 9405dfe476c9416c792724a26ea30e5a7e5d8a40.
Revert "up and down keys allow navigation through history"

This reverts commit 961927cd9dfe6df2fa0f71dfeffc11ff2a286dc7.