Add support for a -h home argument so can easily run in a target directory.
Add configuration support for categories of checksums (10% on, 10% off,
80% uncompressed, by default).

Only run single-threaded 10% of the time (previously, 25%).
Make the random number config use consistent, 1-to-X everywhere instead of
0-to-(X-1) in a few places.
Make the case statement consistent with other use in this program.
Make bloom_oldest configurable for LSM runs.
Typo
shorten the line so we don't overflow when the numbers get large.
Add a bunch of the newer LSM configuration options, but leave turned off
for now.