added case for german languaged Worksheets

[OliverZ]

added case for german languaged Worksheets to not log "Unrecognized key in Heading Pairs" error to console.

[redchair123]

Can you share a file from a german version of Excel? A blank file is fine, I just want one that shows the German case.

Also, can you also modify the master branch as well? Add the same case in xlsx.js and bits/70_xlsx.js

[OliverZ]

i added a testfile here

https://github.com/OliverZ/js-xlsx/blob/master/tests/test.xlsx

if you run

var XLSX = require('xlsx')
var xlsx = XLSX.readFile('test.xlsx');
var sheet_name_list = xlsx.SheetNames;
xlsx.SheetNames.forEach(function(y) {
  for (z in xlsx.Sheets[y]) {
    if(z[0] === '!') continue;
    console.log(y + "!" + z + "=" + JSON.stringify(xlsx.Sheets[y][z].v));
  }
});

it will print: Unrecognized key in Heading Pairs

[redchair123]

I turned off that error message, as it appears to work properly. I'm trying to find a comprehensive list of the possible words, but that is proving hard to find.