README: Convert to reStructuredText.
dhcpd: Replace erratic INADDR_BROADCAST with a targeted subnet broadcast.
dhcpd: Clean-up to follow Python comment and __main__ conventions.
dhcpd/tftpd: Harmonize indentation; mark scripts as executable.
tftpd: Clean-up, follow Python __main__ convention.
dhcpd: Replace use of `eval` with lambda function.
dhcpd: Don't hexlify incoming messages for parsing.
dhcpd: Clean-up lease table.