app enhancements - Feeds/SIDs - sorting/searching/showing humans only

[nanometrenat]

Using Serval Chat in the field (mainly Oct/Nov versions around 116) we identified several easy changes to the All Feeds screen (where users must go to find and add contacts) that would make a lot of difference to user experience/usability:

1. have the option to sort public feed a) alphabetically and b) by most recent
2. hide the Mesh Extender device SIDs by default, so only humans are shown (though still need to be able to find the ME device feeds somehow)
3. add a search function, to quickly find the person you're looking for

[nanometrenat]

Note also - we identified a few oddities that require further investigation - e.g. on my phone, Paul's Prof identity (that I had previously seen correctly) was showing only his SID (not name) in my contacts, and was not showing AT ALL in the feeds. Further testing needed before exact scenarios can be identified, but need to keep an eye on this.