Hi!

I ran into a file that contained a bunch of formulas and external references in <definedName>s, which caused this crash:

     Error: Out of bounds. Invalid column letter: OFFSET
      at Object.l2n (lib/utils/col-cache.js:60:13)
      at Object.decodeAddress (lib/utils/col-cache.js:97:24)
      at Object.decodeEx (lib/utils/col-cache.js:189:24)
      at CellMatrix.addCell (lib/utils/cell-matrix.js:19:29)
      at lib/doc/defined-names.js:159:18
      at Array.forEach (<anonymous>)
      at lib/doc/defined-names.js:157:26
      at Array.forEach (<anonymous>)
      at module.exports.set model [as model] (lib/doc/defined-names.js:155:11)
      at module.exports.set model [as model] (lib/doc/workbook.js:206:30)
      at lib/xlsx/xlsx.js:348:31

Turns out it's caused by what looks like a rather naive range extraction algorithm that doesn't take into account that the defined names could contain double quoted strings or formulas.

I'm unable to share the original file in its full glory, but I made a new one that reproduces one variant of the error.

I'm really not sure that this is the right fix -- it would probably be better to implement proper tokenization/parsing in extractRanges so that the full syntax is understood. Then again, that would be a lot of work, and to be honest I'm have no idea if those ranges are even used for anything important during the parsing?