gotypes,build: pointer dereference (#61)

Provides a method on `gotypes.Component` to allow pointer dereference. This will enable `gotypes` helpers to be used with struct pointer arguments, for example.

Updates #53 
Fixes #54

examples/args/args_test.go

@@ -1,6 +1,7 @@
 package args
 
 import (
+	"math"
 	"testing"
 	"testing/quick"
 )
@@ -36,3 +37,12 @@ func TestFunctionsEqual(t *testing.T) {
 		}
 	}
 }
+
+func TestDereferenceFloat32(t *testing.T) {
+	expect := float32(math.Pi)
+	s := Struct{Float32: expect}
+	got := DereferenceFloat32(&s)
+	if got != expect {
+		t.Errorf("DereferenceFloat32(%v) = %v; expect %v", s, got, expect)
+	}
+}