Eliminated some dead code. In other cases, exported a currently unused
function, since it was a logical part of the API.
Of course this improves the API documentation. It may also sometimes
let ghc optimize code better, since it can know a function is internal
to a module.
364 modules still to go, according to
git grep -E 'module [A-Za-z.]+ where'
ghc 8 added backtraces on uncaught errors. This is great, but git-annex was
using error in many places for a error message targeted at the user, in
some known problem case. A backtrace only confuses such a message, so omit it.
Notably, commands like git annex drop that failed due to eg, numcopies,
used to use error, so had a backtrace.
This commit was sponsored by Ethan Aubin.
