Add the "varint.c" utility program in the tool directory.
Simplify the math slightly, and reduce by one the number of loop iterations,
for the loop in balance_nonroot() that moves cells between pages.
Simplify the logic in the cell redistribution loop of balance_nonroot().
Enhance and clarify comments and add assert() statements for additional
verification of correctness.
Change the command-line shell man-page to use the ".tr" troff directive
instead of ".cc" for escaping the initial "." characters in the ".help"
output.