Too slow when converting some ODS files

[naoliv]

Originally from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=545551

Sometimes odt2txt gets too slow when converting some ODS files.
For example, using this spreadsheet (it isn't exactly a big file: it has 16196 rows X 10 columns) it takes 14+ minutes to convert it.

Maybe this could be improved somehow?

[dstosberg]

Yes, this could probably be solved by a complete rewrite. The whole approach, which is to convert the document by using regular expressions, is flawed. It doesn't scale to large documents. What we would need, is a new tool using a proper XML parser.