Adds auto-generation of all-test-histories.js
Test app imports all-test-histories.js

And a unit test verifies that it works
Improved plan for next steps
Makes test history scrollable without moving tabs
Adds Reset button to test app
Improves button appearance in test app
Removes unneeded code, plus related renamings

HTML5 says element ids are global variables, so my loop that makes this
so is unneeded.  But therefore elements need to be named things that
aren't already global variables.  This commit includes both updates.
Bug fix: Reset did not update maindiv variable
Bug fix: Prevent LE setup from being undone
Factor test app run button code

Useful for upcoming changes (next commit)
Add undo button to test app
Makes test app yes/no buttons for *each* state
Saved histories can be compared to current one
Saved history commands now have run buttons
Can replay full test histories with one click
Added test app documentation