Fix for table row spanning

Fixes a bug where Word tables with vertical spans were not calculated correctly.

See https://github.com/dita4publishers/d4p-word2dita/tree/master/sample-data/word2dita for sample style-to-tag maps and other stuff.

Fixes issue 23, failure to handle hyperlinks within footnotes

Fixes the processing of hyperlinks within footnotes--the lookup of the hyperlink target failed because it was using the wrong .rels file.

Also refined the handling of hyperlink contents so that it only uses within the content if there are different character styles within the hyperlink text.

New tableWidthsProportional parameter

Adds a new parameter, tableWidthsProportional=yes|no, that controls whether or not the column widths for generated tables are specified as absolute widths or proportional. The default is "no", meaning the column widths reflect the actual width of the columns as defined in the Word doc. A value of "yes" results in proportional values.