* improvements to dhcpv4 server
* begin adding examples/httpserver
* add better VLAN tagging methods
* pcap: add error printing; fix bug in CRC
* ipv4: ToS and Flags construction and flag manipulation improvements
* add dhcp interception to httptap and improve httpserver example
* Simplified checksum calculation and verification
* Fixed tests
* UDP: using NewBoundedFrame to create a Frame instance limited to the actual frame size.
* Minor: renamed some functions
* Commented and made more readable consecutive SetCRC calls.
* Fixed icmp checksum calculation after rebase
* Replaced NewBoundedFrame with explicit validation
* add prints to investigate slowness
* add loop sleep for blocking Stack
* add connection close http attribute and detect end of HTML page
* add timeout to bridge read
* examples/xnet: add ntp timestamp to prints and show output in readme
* add polling to http tap interface
* more digits in ntp format
* prevent crashes on non-8 timestamp