fix: panic for some map and pointers

[jxskiss]

Fix:

1. panic when encoding struct with nil pointer field
2. panic when encoding struct which has only one map field
3. wrong bool value marshaling caused by un-reset of pendingBoolField in compact protocol
4. return value of ReadBinary in sbinary must be copied

Change:

1. allow encoding and decoding struct field with FieldId 0, to be compatible with apache thrift rpc response

The changed tests addressed the above issues, all have been fixed now.