Fixes for LineProfile plugin
Fixes for LineProfile plugin

- don't pop up annoying error message if an axis was not selected
- don't rebuild axes controls if image has not changed, only slice

naojsoft/ginga,naojsoft/ginga,ejeschke/ginga,naojsoft/ginga,ejeschke/ginga,pllim/ginga,pllim/ginga,pllim/ginga,ejeschke/ginga