* Use `github.com/pkg/errors` instead of `errors`
* Use `errors.Wrap()` instead of constructing error message by `fmt.Errorf()` or string concatenation
* Use `errors.Errorf()` instead of `fmt.Errorf()`

Fix plugconf template

Fix newline

- Replaced s:config() with s:on_load_pre() and s:on_load_post()

Allows editing the plugconf file(s) of the given repositories.

Closes #230

There are still a few FIXMEs in the code.
The most important one being:

- Which error codes to use?
  Currently 15 and 20 are used, but the existing error codes are not
  documented. It is unclear whether to reuse an existing one or which to
  use for which purpose.

The remaining ones are more about clean code and a different option

add zsh completion

Thanks @sago35 for report.
https://twitter.com/sago35tk/status/1078479020738543616

Co-Authored-By: hupfdule <[email protected]>

Update plugconf examples function names

Place plugconf comments outside of functions again

Co-Authored-By: hupfdule <[email protected]>

Introduce new subcmd `edit`

…258)

Merge #276 into devel branch