This groups non-decimal values by fours, such as bbb_bbbb_bbbb. It also
supports `{:_d}` to use underscore for decimal numbers (grouped in threes).
Use of incorrect ":,b" is not diagnosed.
Thanks to @dpgeorge for the suggestion to reduce code size.
Signed-off-by: Jeff Epler <jepler@gmail.com>
All tests in basics/ directory can now run and pass using 64-bit unix
port with only a 16k heap (./run-tests --heapsize 16k). Tests in this
directory should remain small so they can be used for ports with a
small heap.
Eg: '{:{}}'.format(123, '>20')
@pohmelie was the original author of this patch, but @dpgeorge made
significant changes to reduce code size and improve efficiency.
