Support for encoding/decoding for basic types

[okomestudio]

To support loading/saving from various config file formats, there needs to be a layer that does encoding/decoding to data that those formats understand.

We cannot deal with this in an open-ended fashion, but we could support encoding/decoding of basic types, with a method to extend to user-defined, arbitrary types.

The tables below summarizes data types the supported config file formats support:

Format	str	int	float	bool	datetime	null
INI	x
JSON	x	x (number)	x (number)	x		x
TOML	x	x	x	x	x	x
YAML	x	x	x	x		x

Format	sequence	mapping
INI
JSON	x	x
TOML	x	x (table)
YAML	x	x

The goal is to find the greatest common devisor to support.