Update localization libraries.
Don't delete old core config.

Instead, let it live on, so that it exists for those who still have older
versions. Downside is that it may not be kept in sync, but I think this
is the less painful approach.

As a result, don't complain if there is a `core.$engine` config *and* a an
`engine.$engine` config.

Also fix l10n to be on single lines, so that parser can find them.
Double-quoted string for newline.
Don't migrate core.$engine if engine.$engine exists.

Instead, emit a warning that `core.$engine` still exists and how to
remove it. Also note how to remove it after it has been migrated.
Update l10n libraries.
Make Inline::C install verbose.

To try to find out what its problem is.
Well, now Inline::C builds fine.
Okay, install Inline::C separately. Whatever.
Tweak changes and timestamp v0.997.
Increment to v0.998.
Prevent `update-config` from updating the wrong files.
Merge branch 'master' of https://github.com/theory/sqitch into theory-master
Merge branch 'theory-master'