Replaced pin images with inline SVG

[talk-show-host]

Allows a far greater number of pins to be able to be shown, rather than being limited by number of images (~150 previously). Blue pins now appear on the map. Pins in both the table and the map have been changed. The SVG is saved inline in the JS, rather than as an external file, so colour and text can be changed within the code. Also a prettier pin can be easily made and used, with the SVG code replacing what is currently there. Decided to leave getColorString() alone, so there is a hacky if to choose the colour. I wasn't sure where else that was used, and didn't want to break this unwittingly.