Close #Iss218
Removed is_collapsible_start/end properities
made line_container private
collapse_button can not be toggled if not is_collapsible
renamed is_collapsable to is_collapsible
Removed obsolete lines Made is_prompt_line use original_output_line
Implement paste functionality

Based on work by Nick Ashley and Eugene Golendukhin
Update about dialog credits
fix collapse button staying red bug by not showing collapse button :P