Style refactors

[niklaslong]

Closes #59.

Changes I included:

• use def func(), do: syntax for one-line functions
• remove single pipes
• start pipes with raw value and not a function call
• use pipes instead of reassignment where possible
• use __MODULE__ where possible
• consolidate aliases under same namespace with Mod.{ModA, ModB}

Changes I didn't include (i.e. larger refactoring opportunities).

• doctests, see Run tests on documentation examples #63
• nested control flow (making logic hard to follow)
• large functions should be broken up into smaller ones doing only one thing
• pattern matching in function heads should be mainly used for control flow
• module imports spacing, I've left this mostly as is, as it's mostly down to personal preference

[oliverbarnes]

This is great 🙌 Nicely scoped, and the codebase already feels cleaner and more idiomatic.