Start working on deBruijn indices.  Things will all break soon, so
we are on a branch.
eliminate the "ts_context" from the environment, by implementing
its function using the "tts_context"
remove the "interactive" flag from the environment
change the order of substitution variables from
    x$ |-> x |-> e
to
    x |-> x$ |-> e
because in LF, the type of x$ (which is something like "hastype x T")
depends on x.
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
eliminate white space at ends of lines, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, nothing works
in the middle of shifting to relative indices, not all working