Update to work with leaflet >= 1.7

[kragoth]

I'm not sure if this repo is being maintained at the moment.
So, I've created a fork https://github.com/kragoth/Leaflet.FreeDraw

My fork contains some changes to make the freedraw tool work better with touch devices and leaflet 1.7.
I have only tested my changes on desktop chrome and android chrome so, it is highly likely that they do not work in other browsers.

However, if the author wants to look at incorporating what I've done please do.
This is by far the best drawing tool for leaflet I have found so, I'm really hoping it can stay maintained.