Export Excel and other spreadsheet related goodies

Integration with Excel (or other Spreadsheets) files is a very common request in the software industry, and Smalltalk is lacking an open source tool to offer that feature. This project basically aims to get Pharo and other open source Smalltalks to be able to export Excel and/or other Spreadsheets formats, so the systems that require serving real spreadsheets don't have to keep using the CSV file format as a substitute.