Convert To and Possibly From YAML

[rvare]

After some consideration, it might be a good feature to be able to have YAML conversion.

The proposal is as follows:

• Be able to at least convert to YAML from the other formats.
• Be able to if possible to convert from YAML to other formats.

Some things to consider:

• What should the default indentation be?
  • A tab or two spaces?
• How to determine if a | should be used or > for some fields.
• How to handle #?

If you can think of other possible issues, comment below.