shfmt: insert space after Not

[kristiandueholm]

Purpose

Attempts to solve #987 regarding history expansion triggered by missing whitespace after !.

Changes

I simply added a call to the printer's space function when the unary operator is a Not.

Questions

• Should I add a test of some sort?
• Should I add a check for compact, and omit the space if true? It "breaks" if the space is omitted, but I really am not sure if compact is considered "dangerous".

Thanks!

Closes #987

[kristiandueholm]

I should have run tests before pushing. My bad.

[kristiandueholm]

Really unsure if this is what you were looking for. Running the original tests in interactive shell causes event not found, so I am guessing they had to be changed.