Allow mobanfile to include data from arbitrary config files

[jayvdb]

Currently a mobanfile can only include one overrides: to list a yaml file which contains more settings.

In order to split input data into multiple files, the following is needed: A.yaml overrides: B.yaml overrides: C.yaml

However B and C may have unrelated set of data, so it is an annoyance that B should refer to C.

This also reduces re-usability.

Another project (Z) might want to use the values in B , but not the values in C.

A should be able to directly include B and C, while Z includes B only.

[jayvdb]

An approach which requires little introduction of new terminology or concepts is to allow overrides: to be an mapping.

A.yaml:

overrides:
  B.yaml:
  C.yaml:

...

but still support the old shorter syntax
Z.yaml

overrides: B.yaml

...

For this approach, it would be very acceptable that B & C are not allowed to have the same keys, because there is no defined order in how they should be merged (which is why it is a mapping instead of an array).

This could then be extended to have the mapping value select only a subset of values to be obtained from the mentioned files. e.g.

A.yaml:

overrides:
  B.yaml: translations
  C.yaml: dependencies

...

And array syntax is available in the future if there is a need to have mutliple includes which contain the same keys.

[jayvdb]

The other place where multiple yaml files could be introduces is the inner configuration: key.
i.e.

configuration:
  template_dir:
    - "setupmobans:templates"
    - ".moban.d"
  configuration:
    moban.yml:
    other.yaml:

and

targets:
  - output: CHANGELOG.rst
    template: CHANGELOG.rst.jj2
    configuration:
      changelog.yml:
      mobanfile:

The latter example could be used to remove the name and organisation keys in changelog.yml , which duplicate values in mobanfile.

[chfw]

overrides definition is somewhat changed to include in C/C++, or '@import' in scss:

so a yaml file (A) can include any number of header(yaml) files and keys in A will override any in the included yaml files.

Then in the list of yaml files in A's include list, keys in latter ones will override former ones. I.e.:

overrides:
- B.yaml
- C.yaml

keys in C will overrides B.

[chfw]

the following syntax will introduce order

overrides:
  - B.yaml
  - C.yaml