Crash: Range invalid bounds in XMLStackParser.swift

[JoeMatt]

Line 59,

If xmlParser.lineNumber is 0 this will throw

 for i in 0..<xmlParser.lineNumber - 1 {
            errorPosition += lines[i].count
        }

Fix locally with

        let rangeMax = max(xmlParser.lineNumber - 1, 0)
        for i in 0..<rangeMax {

Not sure if this logic if correct though, instead of throwing or skipping the for loop.

[MaxDesiatov]

Thank you for reporting this @JoeMatt. This is fixed in #84.