raco pkg: fix documentation indexing for user-scoped re-link

If a package installed as a link in user scope, then removed, then
linked again, the documentation index database was not updated
correctly. As a result, the user-specific documentation page was
either not updated or had a broken link for the document.
raco exe: attempt to fix problem with room made for runtime-paths table
fix performance bug in `equal?` on vectors
add some extra test cases on `equal?` and chaperones

The compiler defeated my original attempt to check arguments in
both orders, but now I see the obvious way to (probably) check
both orders.