Bug fix: selected portal unselect if portal re-render
Preserve and restore "selectedPortal" between re-render
Bug Fix: selected portal unselect if portal re-render
Add a checking: if portal is not visible on map, don't preserve "selectedPortal"
Merge pull request #186 from Xelio/patch-selected-portal-unselect-bug

Bug fix: selected portal unselect if portal re-render