update SwissSkullStripper

Changed icon url to an image residing on the wiki.
Merge pull request #344 from lorensen/update-SwissSkullStripper

update SwissSkullStripper
add explicit depends on Editor and verify builds on linux and windoze
Merge pull request #345 from pkarasev3/update-KSlice

add explicit depends on Editor, use git-read-only url
update SwissSkullStripper

Following JC's instructions, changed the scmurl to use the git
protocol.
Merge pull request #346 from lorensen/update-SwissSkullStripper

update SwissSkullStripper