cherrytree 0.19 issued

• before saving a new version of the file “file.ctd”, the former version is now backupped as “file.ctd~”
• introduced a new file format “.ctz” which is the “.ctd” compressed and password protected using 7zip (the binary executable 7za). to switch between .ctd and .ctz click the menu item “file–set document protection”.
• implemented the utility to change the case of the selected text/underlying word