This fixes the error displayed when quitting the pager with long output.
It also replaces the pager lib with more robust homegrown pager utilities,
which should prevent a number of failure modes.
hledger CMD --info will now open CMD's info node,
hledger CMD --man will scroll the man page to CMD's section, and
hledger help -i/-m/-p TOPIC will do similar.
This is not perfectly robust but hopefully will be good enough in
practice.
Also the help command's long --info/--man/--pager flags have been
dropped in favour of -i/-m/-p.
Per feedback from peti. These files will no longer be installed to
cabal's data directory, where it might seem as if they are required at
runtime, which they are not. Packagers will still find them in the
tarball and can put them in the proper place.
You can select a docs format/viewer with one of the `--info`, `--man`, `--pager`, `--cat` flags.
Otherwise, it will use info if available, otherwise man if available,
otherwise $PAGER if defined, otherwise less if available, otherwise it
prints on stdout (and always prints on stdout when piped).
Preferring info over man might not suit everyone.
The hledger package tarball now contains a copy of the generated docs
from all the other packages, so that it can build without being in a
source tree.
