doc/go1.3.html: math/big's Int and Rat implement TextMarshaler, TextUnmarshaler

https://code.google.com/p/go/source/browse/doc/go1.3.html?r=900650e66b4f3431cdef2271ce00813813c466bf

cmd/cgo: given typedef struct S T, make C.T and C.struct_S interchangeable

https://code.google.com/p/go/source/browse/doc/go1.3.html?r=177ed19da89fc68391d6e2411163ffe777180637
doc/go1.3.html: translate test rest to Japanese. refs #44
Merge pull request #46 from t-yuki/master

./doc/go1.3.html update