Add option to disable parser for chunks of code

[kdkavanagh]

Recently ran into the issue discussed in #79. It's not important for my usecase, but I do still want the parser to continue to parse the file if possible. What are your thoughts on a syntax like the following to allow the parser to skip chunks of code known to break the parser, (similar to disabling clang-tidy checks over a range of code)?

class MyClass {

// CXXHEADERPARSER_IGNORE_START

// as an example of something the parser cant support:
typedef  int (Fred::*FredMemFn)(char x, float y);

// CXXHEADERPARSER_IGNORE_END

}

[virtuald]

Well if we're copying clang-format...

// cxxheaderparser off

// cxxheaderparser on

But there's a lot of ways to bikeshed this.

[auscompgeek]

You could also put it through a C preprocessor with some #ifndef guards.