Improve config file structure

[Riey]

Motivation

Now, config file is hard to deal with default config

it's unclear which option will use default value

Progress

• Load configs
• Make basic config files

Solutions

Don't use default value at all

It's impossible to get small config file but very consistent

Don't use structural config

Write config file as key, value pair and it'll override default config

[Riey]

Implemented on breaking/rework-config branch