ditch duff comment
* Introduce patrol area to generate target location
* Allow pause button to also resume
* Introduce features to display
Minor refactoring of how icons added
* Move the category utilities into geo.js
* refactor global vars
* use local leaflet JS sources
* move scenario to extenal file
correct deliberate typo
Introduce leaflet standard images
Support single vessel, with no sonar
Introduce objectives
Introduce game-state object