Refactor code of select/unselect portal. Add hook 'portalSelected' with guid of selected and unselected portal.
Plugin bookmark for maps and portals: Change to use hook 'portalSelected' to remove star instead of modify window.unselectOldPortal().
Fix comment.
Merge pull request #537 from Xelio/hook-select-portal

Refactor code of select/unselect portal. Add hook 'portalSeleted'.