meshviewer-ffrgb output: add custom fields

This will include all configured custom fields in the meshviewer-ffrgb output
under the "custom_fields" key.

output/meshviewer-ffrgb/struct.go

@@ -41,6 +41,7 @@ type Node struct {
 	Autoupdater    Autoupdater            `json:"autoupdater"`
 	Nproc          int                    `json:"nproc"`
 	Model          string                 `json:"model,omitempty"`
+	CustomFields   map[string]interface{} `json:"custom_fields,omitempty"`
 }
 
 // Firmware out of software
@@ -154,6 +155,12 @@ func NewNode(nodes *runtime.Nodes, n *runtime.Node) *Node {
 			node.GatewayIPv6 = statistic.GatewayIPv6
 		}
 	}
+	if customFields := n.CustomFields; customFields != nil {
+		node.CustomFields = make(map[string]interface{})
+		for fieldName, fieldValue := range customFields {
+			node.CustomFields[fieldName] = fieldValue
+		}
+	}
 
 	// fix site to domain - if empty
 	if node.DomainCode == "" {

output/meshviewer-ffrgb/struct_test.go

@@ -58,6 +58,10 @@ func TestRegister(t *testing.T) {
 				},
 			},
 		},
+		CustomFields: map[string]interface{}{
+			"custom_fields": "are_custom",
+			"custom_int":    3,
+		},
 	})
 	assert.NotNil(node)
 	assert.NotNil(node.Addresses)
@@ -66,4 +70,6 @@ func TestRegister(t *testing.T) {
 	assert.Equal(13.3, node.Location.Longitude)
 	assert.Equal(8.7, node.Location.Latitude)
 	assert.Equal(0.74, *node.MemoryUsage)
+	assert.Equal("are_custom", node.CustomFields["custom_fields"])
+	assert.Equal(3, node.CustomFields["custom_int"])
 }