tests: Move Graphite and "long line" data definition out from main test table

Having that long data makes the table clumsy and harder to understand.
By moving such data definition out of the table, we make it a bit easier
to understand.

In the case of "long line", the pickle input and the line itself were
almost duplicating each other, so instead of having two long lines
explicitly pasted, let's have the test input be defined as

+	{"too long line", "V" + longLine + "\n.", longLine},

In the case of Graphite messages, one long Graphite object was also
duplicated in encode_test.go .

Just a cleanup, no semantic change.

encode_test.go

@@ -21,7 +21,7 @@ func TestEncode(t *testing.T) {
 	}{
 		{
 			"graphite message",
-			[]interface{}{map[interface{}]interface{}{"values": []interface{}{float64(473), float64(497), float64(540), float64(1497), float64(1808), float64(1890), float64(2013), float64(1821), float64(1847), float64(2176), float64(2156), float64(1250), float64(2055), float64(1570), None{}, None{}}, "start": int64(1383782400), "step": int64(86400), "end": int64(1385164800), "name": "ZZZZ.UUUUUUUU.CCCCCCCC.MMMMMMMM.XXXXXXXXX.TTT"}},
+			graphiteObject1,
 			nil,
 		},
 		{