Add more features for working with POI

[Martin Kolman]

• fast add with a long-press on the map
• search the list with typing
  • plaintext search ?
• display all POI on the map
• manually toggle POI visibility per POI/group
• show POI based on some rules
  • show all POI in N km radius around current position/view
  • some other rules :)

• POI overlay - combine visibility triggers for individual POI and group + rules to custom layers

• show all poi on the currently visible map

• tag support
  • would need a new db table, that would need to be named as not to collide with mappero

• display a counter and list of visible POI
  • easy jumping between visible POI

• POI colors & icons

• smart label display (would be also useful for local search results)