Plugin: What portals can I upgrade, together with a group of other agents

Based on vita10gy's portal-highlighter-can-make-level.user.js. Allows players to add other agents to their group, and highlights portals upgradable by the group. Agent names are autocompleted in the desktop version, and searchable on mobile. If a guessed player level is available (in local storage) then the player level is initially set to the guessed level - otherwise 8. Levels can then be modified manually.