Fix HTML Layout. Support multiple formats at once. More handling. This commit is a bad mix of multiple changes. It addresses: - HTML Width is now relative and should fix some pdf creation problems. - Format is now taken from the extension of the file names provided. - Multiple file names are accepted at once. - Parser now handles missing values in Multiple choice answers - Parser now handles unfilled multiple choice values

This is the QtXlsxWriter library from http://qtxlsx.debao.me

Based on git rev. ad90b6a

Added CMake Build system for tooling convenience.