Reduce initial allocation to 1 MB now that it can by increased at runtime.
Also remove 'noreturn' attribute from the public API.
If out_of_memory() returns, GC will abort() internally.
Fix tree_replace() to handle recursive data structures.
Fix some other minor bugs in the reader and interpreter.
Implement comment-escapes in the string parser, for more readable input.
Allow input program files (*.rla) to be invoked directly, with arguments.
Add a simple string->number converter as a builtin function.
Jesse D. McDonald