and non-mutated identifiers. helps a lot with the default
syntax-rules constructions - in particular reduces the number of
bytecode allocations for (chibi match) from 2397 to 1872.
can disable with USE_BIGNUMS=0 - the interactions between this and
USE_FLONUMS are messy, so they will likely be merged into a single
option in the near future (i.e. you either have only fixnums, or a
full range of numeric types).
adding rationals based on this would be easy and is a likely future
feature. adding native support for complex numbers is unlikely.
