Fix the assertion assert introduced in r34348 which got fired when eg. deselecting...

Fix the assertion assert introduced in r34348 which got fired when eg. deselecting an InsetCommand:

- we have to have a copy constructor in InsetCommand to clear the mouse_hover_ map and not to copy it,
- there is no need to have mouse_hover_() in the initialisation list,
- there is no need to copy the auto_open_ map.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@34353 a592a061-630c-0410-9148-cb99ea01b6c8