Check and Fix some issue#1535
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
1.doxgen documentation format for comments in api/*.h 2. comments to wiki tools in openh264/docs/*
Merge pull request #1544 from shihuade/master

1.doxgen documentation format for comments in api/*.h 2. comments to wik...
Merge pull request #1543 from dongzha/Fix1535

Check and Fix some issue #1535
add some traces
Merge pull request #1545 from ruil2/add_traces

add some traces