solface now generates more meaningful names for some compound types

For compound types which are structs, the names are now much more human
readable assuming that the input ABI defines their `internalType`
fields.

Also updated the GitHub action to use the new `-version` flag to print
the version.

.github/workflows/test.yml

@@ -15,4 +15,4 @@ jobs:
           go test ./... -v
       - name: Print solface version
         run: |
-          go run ./... -h 2>&1 | tail -n1
+          go run ./... -version

abi.go

@@ -15,9 +15,10 @@ type TypeDeclaration struct {
 
 // Represents a value in an ABI.
 type Value struct {
-	Name       string
-	Type       string
-	Components []Value
+	Name         string
+	Type         string
+	InternalType string `json:"internalType,omitempty"`
+	Components   []Value
 }
 
 // Represents a parameter for an event in an ABI.

interface.go

@@ -63,9 +63,25 @@ func GenerateName(nameCounter *int) string {
 	return result
 }
 
+// Parses the name of an internal type and either returns that name (for structs) or "Compound" (for
+// any other type).
+// For nested structs (e.g. structs defined in other contracts or interfaces), this only returns the
+// final component of the name.
+func ParseInternalType(internalType string) string {
+	if !strings.HasPrefix(internalType, "struct") {
+		return "Compound"
+	}
+
+	structQualifiedName := strings.TrimPrefix(internalType, "struct ")
+	structNameComponents := strings.Split(structQualifiedName, ".")
+	structName := structNameComponents[len(structNameComponents)-1]
+	return structName
+}
+
 // Generates a fresh name for an anonymous compound type.
-func GenerateType(typeCounter *int) string {
-	result := fmt.Sprintf("Compound%d", *typeCounter)
+func GenerateType(typeCounter *int, internalType string) string {
+	typeName := ParseInternalType(internalType)
+	result := fmt.Sprintf("%s%d", typeName, *typeCounter)
 	(*typeCounter) += 1
 	return result
 }
@@ -168,7 +184,7 @@ func CompoundSingleValue(val Value, typeCounter, nameCounter *int) (Value, []Com
 	}
 
 	var compound CompoundType
-	compound.TypeName = GenerateType(typeCounter)
+	compound.TypeName = GenerateType(typeCounter, val.InternalType)
 	compound.Members = make([]NamedValue, len(updatedComponents))
 	for i, component := range updatedComponents {
 		memberName := component.Name