Visualise hatchling fan angles

[florianm]

Create a new R package leaflet-hatchlings

• Template for R package wrapping Leaflet functions: leaflet.extras
• Leaflet plugin to draw semicircles: Leaflet-semicircle
• Add helpers to translate wastd_data$nest_fans/nest_fan_outliers/nest_lightsources to data for Leaflet-semicircle
• Use any other Leaflet plugin to visualise
• Write-up of data and draft spec for visualisation see https://github.com/dbca-wa/Leaflet.Hatchlings (this repo can then probably go away, seeing all necessary Leaflet vis components already exist - semicircle, lines, points)

[florianm]

Leaflet.Circle-sector wrapper created as a new R package: https://dbca-wa.github.io/leaflet.circlesector/
Now we can add wastdr::map_fanangles as:

• Prepare data as per generate_data
• Plot data as per vignette "Introduction"
• Integrate into turtleviewer2

[florianm]

Should refactor the data prep for fan angles into download wastd turtledata and use pmap for performance on mis_bearing and mean_bearing

[florianm]

Refactor done: expensive rowwise() calculations of misorientation and mean angles are pushed to download_wastd_turtledata.
TODO: should write a wrapper for https://github.com/jieter/Leaflet-semicircle/blob/master/Semicircle.js which is available on npm using derivePoints and invokeMethod and see if we can leverage vectorised leaflet::circle().