Builtin requests

[ngoodman]

Here a a single issue for all issues of the form "primitive X is not implemented".

If you have more please list them as comments.

(Note functions that can be implemented in church easily are low priority, but will likely get added eventually.)

[ngoodman]

iota, zip, filter

string-append, string-trim --- more generally string stuff

save, load, write (should happen soon, and be tied to parameter passing for node runscript). display (depends on webworker transition?).