ElvUI BetterTalentFrame adds specialisation tabs much like the pre-Legion dual specialisation tabs. These tabs allow the player to view their non-active specialisation's talents at any time.
Other improvements include being able to switch specialisation on any tab of the talent frame and saving/loading custom talent profiles.
Talent profiles allows you to save and apply talent configurations with a single click. Profiles are saved per class/spec (i.e. all your feral druids will have access to the same profiles). You still have to be in a city or inn (or have a talent change buff active) to be able to change and apply profiles, but simply managing your profiles can be done anywhere.
ARWICTP_ActivateProfile(profileIndex)
/equipset AoE
/run ARWICTP_ActivateProfile(2)
-- activates talentprofile with ID <profileID>
-- IDs starting with 1
/talentprofiles activate <profileID>
-- cycle through talentprofiles
/talentprofiles next
-- Info
"/tp" is an alias for "/talentprofiles"