settings: Local Highlights, default Current nick

settings: Local Highlights, default Current nick

Re-enable nickname highlighting in Local Highlights by default.  This
fixes the issue of upgrading the client before the core resulting in
loss of nickname highlighting.

Many other options were discussed, such as unifying these settings
(new UI work), automatically toggling/disabling local based on core
features, auto-importing, etc, and though all better approaches, they
will take a good bit more time to implement correctly.  The focus is
on fixing client-side settings properly in 0.14+, with profiles
allowing for different settings per groups of clients, allowing
deprecation of local highlights entirely.

Partial revert of f2e4560b71a1888599ca2153eee36a9b4136c902 and 5fcc2f000757bb7c2578e09c8fc8c86a288c3cb5