Improved documentation to `dip::Not`, `dip::Invert`, and the unary operators `!`, `~` and `-`, and expanded use of operator `!`.
Improved documentation to `dip::Not`, `dip::Invert`, and the unary operators `!`, `~` and `-`, and expanded use of operator `!`.

DIPlib/diplib,DIPlib/diplib,DIPlib/diplib,DIPlib/diplib,DIPlib/diplib,DIPlib/diplib