v1.2.0

1. use field tag binary:"packed" to encode ints value as varint/uvarint for reged structs.
2. add method Encoder.ResizeBuffer.

V1.1.0

fix issue#1 nil pointer encode/decode error
pack 8 bool values as bits in one byte
put one bool bit for pointer fields to check if it is a nil pointer
rename Pack/Unpack to Encode/Decode

V1.0.0

1. full-type support like gob
2. light-weight as std.binary
3. high-performance as std.binary and gob
4. encoding with fower bytes than std.binary and gob
5. use RegStruct to improve performance of struct encoding/decoding
6. take both advantages of std.binary and gob
7. recommended using in net protocol serialization and DB serialization