Asignee overridding on clone

Fix bug with asignee overridding on clone.

1.1

"New from template" have been reimplemented to be available when using the packed extension.
Options page have also been restructured and redesigned for clarity.
Clone title prefix have been replaced by clone and description prefix and suffix, including the possibility of using replaceable tokens for issue number, issue link and issue title.

Initial release

Basic functionality working: "Clone" & "Clone to".
"New from template" works only if installed in developer mode, not as packed extension.