Pointer cleanup (#78)

Remove unnecessary pointer receivers for Position and QueryResult

position.go

@@ -18,12 +18,12 @@ type Position struct {
 
 // String representation of the position.
 // Displays 1-indexed line and column numbers.
-func (p *Position) String() string {
+func (p Position) String() string {
 	return fmt.Sprintf("(%d, %d)", p.Line, p.Col)
 }
 
 // Invalid returns whether or not the position is valid (i.e. with negative or
 // null values)
-func (p *Position) Invalid() bool {
+func (p Position) Invalid() bool {
 	return p.Line <= 0 || p.Col <= 0
 }