Many more pin images

[simon-brooke]

The set of pin images in the current repo are those needed by the project for which this was originally written. But it isn't much good as a general tool if it doesn't offer a broad range of pin images to pick from.

[simon-brooke]

All pin images should be in PNG format, with the same size and transparency mask as the existing Unknown-pin.png. This is so that the existing shadow can be used with all pins - having separate shadows for different pins seems to me unnecessarily complex. Names must be suffixed with -pin.png. Ideally, each set should have a distinguishing abbreviation, so that the full name of the any pin is <abbreviation>-<base-name>-pin.png.

Pin images should be add in the folder resource/public/img/map-pins