Though these are not as user-facing as other strings, the action names
still are somewhat user-facing. Let's rename them consistently with the
GUI and the API.
This commit also handles user config migration so that custom shortcuts
are not lost.
Though we mostly removed floating layers/masks (formerly floating
selections) in many interactions, at least for default behaviors for
basic pastes, there are still advanced usage attached to this concept
and some advanced users are willing to have easier access to such items.
For this reason, this commit:
- adds edit-paste-float and edit-paste-float-in-place for pasting the
contents of the clipboard as floating data with default positionning
algorithm or in-place respectively;
- renames select-float to select-cut-float which does a cut and paste as
float in one action;
- adds select-copy-float which does a copy and paste as float in one
action;
- reorganize a bit the `Edit > Paste as` submenu with sections for the
floating data variants;
- add a "Float" submenu in "Select" root menu, containing the 2 variant
actions select-cut-float and select-copy-float.
"edit-paste-as-new-image-short" and "vectors-selection-to-vectors-short" were
just duplicate of the action named the same, except for the "-short" suffix, and
the only point was to have different labels.
Not though that this time, it was not enough to conclude that the action in a
menu shoud have the short variant. These were both used differently depending on
the menu.
Instead I added the concept of "label-variant" attribute in .ui menu files. When
the "long" variant is set, then we simply use the longer label.
There is still one more "-short" action: "tools-by-color-select-short", but I am
a still unsure how to handle this one.
Jehan