OSX,Mac modifier key symbols;in the help text line.

[dgud]

Reasons why I changed it:
1) The shortcuts in window menus at the top are automatic by the OSX so we can not change that.
Thus, it is confusing to mix signs in one place and key-names in other places, it is better to be consistent.

2-3) There are not the same since Mac have the command key where Ctrl is used on the
other OS's so they differ anyway.