Bezier profiling

Use bezier curves to create the landmass profile.
Less mountains, more lowlands, deeper seas.

Pretty palette

Heightmap uses a nice palette based on Wikipedia map guidelines
Layers (heightmap/biomes) now switchable in UI
Quite a lot of refactoring and other invisible stuff

Add Dockerfile

This is a maintenance update

Added a Dockerfile, so that it's easier to install and run the generator across paltforms
Updated packages

Biomes

Added biome generation based on Polygonal Map Generation for Game from Red Blob Games article