Rename "for" combinator to "all"
tuned
add support for "for" and tune instantiations

instantiations may have more general types then in theorem -- must be
instantiated
tuned
Nicer error message for failed instantiations
tuned
tuned
tuned
add "to" keyword
at each position, try all theorems (not the other way round)
filter rules against to pattern, before matching
tuned
tuned
forbid vars, dummys and holes in instantiation