FileSelector: move navigatin_locked as a member variable
FileSelector: fix combobox behavior as now ComboBox::onChange() event is generated when the combobox is open
Add #pragma once
Fix header of files distributed under the terms of the MIT license
Fix copy & paste from Indexed to RGB (use the clipboard palette)
Fix image conversion from Indexed to Indexed mapping colors (related to issue #267 and #195)
Move copy/paste of clipboard text from "ui" to "she" library