[crt] Remove inlines in debug-print.c

There's no need for inline functions here.
[crt] Remove unused arg to do_debug_message.
[crt] Flag many functions as static.

Clean up the global namespace.
[crt] Formatting: return isn't a function in C.
[crt] Formatting: Show a love for braces.
[crt] Namespace all external symbols with dylan_.
[crt] Remove some dead code.
[crt] Provide dylan_double_float_p.

This matches the dylan_single_float_p and dylan_float_p.
[crt] Provide a way to dump Dylan values to stdout
[crt] Replace many usages of BOOL with (std)bool.
Merge pull request #450 from waywardmonkeys/improve-crt-debugging

Improve crt debugging