nsams:
Add default shortcuts for moveLinesUp/Down

Eclipse does have Alt+Up/Down but that does something else already in KDevelop,
so use Ctrl+Shift+Up/Down.

improve code sharing as suggested by dominik

if selection ends at beginning of line, skip that line

Select duplicated text

don't duplicate code, instead create private helper functions

remove duplicateLine function, as the new ones do basically the same

add script that duplicates selected lines up/down