using same type as in interface rather than int32 for uiTimestamp to avoid missing of preciseness
add UNSPECIFIED value for max bit rate setting
Merge pull request #1537 from sijchen/after_review

[Encoder] Two refinements related to max bit rate setting and Timestamp
Merge branch 'master' of https://github.com/cisco/openh264 into max_nal_size

Conflicts:
	codec/encoder/core/inc/param_svc.h