Feature/markdown as master

[ShMcK]

closes #40.

Treats the markdown as the source of truth. This means if a level/step isn't in the config, it will still build.

Allows for the new recommended way of labelling levels/steps:

In markdown:

• Level: ## 1. Level one
• Step: ### 1.1 A Label (label is optional)

And in commits:

• 1 Level
• 1.1 First step commit
• 1.1S First step solution