Add bit operators for tweet_flags.
Templatise cached_id_sets iteration functions.
Avoids std::function overhead, makes things more unrollable.
Add utility functions to update tpanel clabel later.
Improve how tweet flag changes/updates are handled.

Make update code somewhat less ad-hoc.
Store value of flags at previous update, to avoid unnecessary updates.
Only handle CIDS for flags which have actually changed.

Changes to tpanel tweet sets which include CIDS auto-source are now
incremental rather than recalculate-and-diff.
This fixes horrendous performance issues when bulk changing CIDS flags in
a filter operation when a panel exists which has the same CIDS set as
an auto-source.
Add make vars to build with gprof, and strip after building. Fix map var.
Update .gitignore.