Set starting topic number

Currently when using topic numbering, the starting number is always set to 1. This limits the value of the auto-numbering feature significantly. A simple example might be level 1 "Section" topics with level 2 "Chapter" subtopics, where the chapters in each section must be numbered sequentially across all sections. Although it would be ideal to attach numbers to topics by type, at least this would allow a simple update within each section and have the rest of the numbers flow automatically. Currently, there is no way to achieve the correct numbering.