* pxDuplicateNetworkBufferWithDescriptor
* pxUDPPayloadBuffer_to_NetworkBuffer NULL
* Add IPv4 Utils
* Add description for unit test and separate IP_Utils/IPv4_Utils
* usGenerateProtocolChecksum
* prvChecksumProtocolCalculate
* Add description of test cases
* pxUDPPayloadBuffer_to_NetworkBuffer & prvProcessNetworkDownEvent & usGenerateProtocolChecksum
* usGenerateProtocolChecksum
* Full coverage
* Remove dedundant include
* Code beautify
* IPv4_Utils full coverage
* Remove redundant include in IPv4_Utils unit test
* Fix IPv4 UT building
* Fix spelling.
* Add macro for minimum TCP offset.
* Fix doxygen
* Fix again
* Move Stub functions to _stubs.c and fix compile warning
* Update diffconfig UT