Fix #686: Add warning for bad line directives

[glankk]

readfile now takes a DUI with information about which standard to use, which is needed to determine if a warning should be issued or not. preprocess now also includes outputs from makeTokenLists which calls readfile. Some tests had to be fixed to have an ending newline because of this in order to pass.

[danmar]

this value might not work well.. it means tokens might get line number 0 which cppcheck interprets as "no line".

I suggest that the value passed in the lineDirective call will be 1. After reporting the error message.. change it to 1?

[danmar]

or assign maxvalue+1?

[glankk]

Sounds good.

[glankk]

Actually it might be better that we just ignore the line number and use the current one when it's out of range, what do you think?

[glankk]

Or just discard the line directive entirely.

[danmar]

I would be fine with both those options.

[glankk]

I've changed it to just use the maximum possible line number, I think that's alright. It's guaranteed to always be representable, and it's also the most lenient option in terms of conditional support.