Cleanup: Remove unused Document.StatusKeywords field & clean len checks

Leftover from the days before BufferSettings & DefaultSettings - now that those
exists the status keywords are actually defined in
- DefaultSettings["TODO"] for the default
- BufferSettings["TODO"] for any customizations

Also ! i < len => i >= len because it's easier on the eyes

org/table.go

@@ -86,7 +86,7 @@ func getColumnInfos(rows [][]string) []ColumnInfo {
 	for i := 0; i < columnCount; i++ {
 		countNumeric, countNonNumeric := 0, 0
 		for _, columns := range rows {
-			if !(i < len(columns)) {
+			if i >= len(columns) {
 				continue
 			}