Skip whitespaces in preprocessor

[Stupremee]

This PR will skip any white spaces that occur in the lex::replace::replace method, to support macro calls where
the identifier and the arguments are separated by spaces (e.g. f ().

Resolves #457

[jyn514]

r? @hdamron17

I'm worried this will lose whitespace again while printing with -E but I'll defer to Hunter's judgement.

[jyn514]

As an alternative you could store the whitespace tokens and yield those tokens if no replacement was found.

[Stupremee]

That sounds like a good idea

[hdamron17]

As long as the macro is actually replaced then it is fine to consume the whitespace. The issue is if you have an id that is the name of a function macro but has is not used as one because it is not followed by a parenthesis. Can you peek at the token following the whitespace?

[hdamron17]

Make a test using assert_same_exact that has both cases of f(...) being replaced and f left as is.

[jyn514]

Suggested change

	Some(Ok(Locatable { data: _, .. })) => {
	Some(Ok(_)) => {

[Stupremee]

The test is still failing with the following error:

left: `"\n\n1\n"`,
right: `"\n1\n"`',

I can't figure out why so you have to look over it.