Fix crash when mixing z-coord dimensionality in a geometry

This commit fixes an issue where the parser allows for some points
to have a z-coord following coordinates that do not. But then the
library will crash when outputing the geometry to geojson.

This fix has the parser return the error "invalid coordiantes"
when parsed.

linestring.go

@@ -183,6 +183,10 @@ func parseJSONLineStringCoords(
 		coords = append(coords, geometry.Point{X: nums[0], Y: nums[1]})
 		if ex == nil {
 			if count > 2 {
+				if len(coords) > 1 {
+					err = errCoordinatesInvalid
+					return false
+				}
 				ex = new(extra)
 				if count > 3 {
 					ex.dims = 2

polygon.go

@@ -231,6 +231,10 @@ func parseJSONPolygonCoords(
 			coords[ii] = append(coords[ii], geometry.Point{X: nums[0], Y: nums[1]})
 			if ex == nil {
 				if count > 2 {
+					if len(coords) > 1 || len(coords[ii]) > 1 {
+						err = errCoordinatesInvalid
+						return false
+					}
 					ex = new(extra)
 					if count > 3 {
 						ex.dims = 2

polygon_test.go

@@ -164,3 +164,18 @@ func TestIssue664(t *testing.T) {
 		}
 	}
 }
+
+func TestIssue714(t *testing.T) {
+	_, err := Parse(`{"type":"Polygon","coordinates":[[[0,0],[10,0],[0,10],[0,0]],[[0,0,0],[0,10,0],[10,0,0],[0,0,0]]]}`, nil)
+	if err.Error() != "invalid coordinates" {
+		t.Fatalf("expected '%v', got '%v'", "invalid coordinates", err)
+	}
+	_, err = Parse(`{"type":"Polygon","coordinates":[[[0,0],[10,0,1],[0,10],[0,0]]]}`, nil)
+	if err.Error() != "invalid coordinates" {
+		t.Fatalf("expected '%v', got '%v'", "invalid coordinates", err)
+	}
+	_, err = Parse(`{"type":"LineString","coordinates":[[0,0],[10,0,1],[0,10],[0,0]]}`, nil)
+	if err.Error() != "invalid coordinates" {
+		t.Fatalf("expected '%v', got '%v'", "invalid coordinates", err)
+	}
+}