"layers-text-tool" action shows as "Text Tool" while "vectors-path-tool"
shows as "Path Tool". That's very confusing with tools-text and
tools-vectors respectively.
These actions are mostly about entering in edit mode with the active
layer or path. For text layers, it will enter text edition on canvas,
whereas just open the attributes edition dialog on other layers. For
consistency, layers-text-edit is renamed as well too layers-edit-text.
This also fix the side effect of commits 10099bda and 526918b2 where I
didn't realize that layers-text-tool was also working on non text layers
on purpose (being very badly named). Now there is a separate layers-edit
and layers-edit-text.
Thanks to Pat David for English corrections. :-)