files. These files mostly mediate between the C source (export) and
the corresponding C stub files (import) generated by the Scheme files
calling the C routines.
This provided much better argument type checking that before; lots of
small bugs were caught.
Also added const keywords wherever I could find a reasonable place
to improve error detection and efficiency.
Tuned up the makefile to reflect all of this structure. Its dependencies
were pretty out-of-date as it was. It could probably use further work.
bdc