bug#13115: prettier pretty-printing for eieio

[Jonas Bernoulli]

Hello

The attached patch implements prettier pretty-printing in eieio.

* don't quote keywords and booleans
* don't insert needless newlines (empty lines, and before closing
  parents)
* align values that are objects with the slot keyword instead of putting
  it's beginning on the same line as the slot keyword.
* similar for lists of objects

Prettier pp:

,----
| (eieio-pp-demo "top"
|   :keyword :keyword
|   :boolean nil
|   :object
|   (eieio-pp-demo "subsub"
|     :list '(a b c))
|   :list '(a b c)
|   :object-list
|   (list
|     (eieio-pp-demo "sub"
|       :keyword :keyword
|       :object
|       (eieio-pp-demo "subsub"
|         :list '(a b c))
|       :list '(a b c))
|     'non-object
|     (eieio-pp-demo "sub"
|       :keyword :keyword
|       :object
|       (eieio-pp-demo "subsub"
|         :list '(a b c))
|       :list '(a b c))))
`----

Not so pretty pp:

,----
| (eieio-pp-demo "top"
|   :keyword ':keyword
|   :boolean 'nil
|   :object   (eieio-pp-demo "subsub"
|     :list '(a b c)
|     )
| 
|   :list '(a b c)
|   :object-list (list 
|    (eieio-pp-demo "sub"
|     :keyword ':keyword
|     :object     (eieio-pp-demo "subsub"
|       :list '(a b c)
|       )
| 
|     :list '(a b c)
|     )
|  'non-object   (eieio-pp-demo "sub"
|     :keyword ':keyword
|     :object     (eieio-pp-demo "subsub"
|       :list '(a b c)
|       )
| 
|     :list '(a b c)
|     )
|    )
|   )
`----

The demo code is also attached.

I have used this code to save the metadata extracted from all packages
on the Emacsmirror without any problems for several months now.

  Please consider merging this, thanks
  Jonas

prettier-eieio-pp.patch
Description: patch

eieio-pp-demo.el
Description: demo