Allow inverting/negating file and line RegEx rules

[j-ulrich]

Often it is impossible or very hard to detect files/lines which do not contain a certain pattern using regular expressions while it is easy to match the files/lines which do contain the pattern.

Therefore, it would be great if the File RegEx rule and Line RegEx rule could be negated to generate an error if a file or line does not match the given regex.
There could be a checkbox on the rule creation popup to enabled/disable the negation.

Example use case: Detect header files without include guards/pragma once

[jmecosta]

I suppose the include guards could be even a rule. We usually require this

[guwirth]

For me this sounds useful. I think it is less effort.

[guwirth]

@j-ulrich please test #536

[j-ulrich]

It works! Thank you! :-)

However, I had to skip the unit tests because they were failing due to path issues with 8.3 path names (I don't have a Linux box around at the moment).

I used this RegEx to detect the include guards: \s*#ifndef\s+(\w+)\s*\n#define\s+\1\s*\n[\w\W]+|[\w\W]*#pragma once\s*\n[\w\W]+