Actions extensions in File Manager - draft 0.7

[Pierre Wieser]

Hi all

The draft has been updated to take into account last comments
from contributors.

- ExecutionMode:
  No more propose Minimized/Maximized modes
  (typo: remove fallback from Terminal mode)

- ForEach key is removed

- Profiles and ItemsList keys become dynamic; the behavior for found
  though not listed subitems is more precisely described

- GetItemsList key is removed

- SelectionCount default is changed from '*' to '>0'

- Added a comment on how string list must be readen in Conditions

- Folders may be negated

We never have been as close of the end ;-)
I'm preparing a status about some points which may require more
discussions or clarifications.

Regards
Pierre