Fix issues mentioned in http://www.tt-forums.net/viewtopic.php?f=29&t=70846&sid=36761c70845b94500dc3724196d2dce0&start=20#p1139434

- Use W,1 rather than W,0 in water lines - option for using zero added
- Fix issue where town size was below smallest limit
- Re-order coordinate input boxes.