Add the --taxonomic-path option to obiannotate

Former-commit-id: 385309a1c4bc5ed33aeaafc63eedb9fc552f78a6

pkg/obitax/taxonslice.go

@@ -1,5 +1,10 @@
 package obitax
 
+import (
+	"bytes"
+	"fmt"
+)
+
 type TaxonSlice []*TaxNode
 
 func (set *TaxonSlice) Get(i int) *TaxNode {
@@ -9,3 +14,25 @@ func (set *TaxonSlice) Get(i int) *TaxNode {
 func (set *TaxonSlice) Len() int {
 	return len(*set)
 }
+
+func (path *TaxonSlice) String() string {
+	var buffer bytes.Buffer
+
+	if len(*path) > 0 {
+		taxon := (*path)[len(*path)-1]
+		fmt.Fprintf(&buffer, "%d@%s@%s",
+			taxon.Taxid(),
+			taxon.ScientificName(),
+			taxon.Rank())
+
+		for i := len(*path) - 2; i >= 0; i-- {
+			taxon := (*path)[i]
+			fmt.Fprintf(&buffer, "|%d@%s@%s",
+				taxon.Taxid(),
+				taxon.ScientificName(),
+				taxon.Rank())
+		}
+	}
+
+	return buffer.String()
+}