Give an early pointer to where to look if 'acprep update' fails.
Clarify a few things in the first section.
Give sections clearer headers, so they can be more easily referred to.
Add a FAQ entry about what to do if './acprep update' gives errors.
Update FAQ entry about MPFR library to refer to above new entry.
Debian squeeze, which is currently the stable distribution at the time of
this commit, has both a Boost and a CMake that is too old for Ledger.
This FAQ entry explains how to build your own Boost and CMake for use with
Ledger, and the exact commands to type to build and install each, and then
configure, build and install Ledger against those new versions.
