Fix python imports in SConscripts

Remove and/or simplify most remaining SENFSCons stuff

Utils/Console: Catch exceptions when closing client
PPI: Add throttle tracing
PPI: Fix Event and IOEvent throttling

Packets: Clean up output formatting in all dump() members
Packets/80211Bundle: RadiotapPacket: Use length header field to get header size
Packets/80211Bundle: Move FCS from WLANPacket to RadiotapPacket
Packets/80211Bundle: Replace WLANPacket variant parsing by three separate packet types for control, management and data frames
Packets/80211Bundle: complete dump() members
Utils/Console: Implement 'ls' command and move old 'ls' to 'll'
Scheduler: ClockService: Handle unset (that is 0) clock_type value explicitly in senf::ClockSservice::abstime()

Socket/Protocols: Implement INet4Network input streaming
Socket/Protocols/INet: Add reuseaddr to connected UDPClientSocketHandle constructor
Utils/Console: Add emptyReplies flag to UDPServer

PPI: Allow IOEvents to be constructed with an in-valid() handle
Socket/Protocols/INet: Implement INet6Address::from_mac()
Socket/Protocols/Raw: Implement LLSocketAddress output streaming

Socket: Remove net/if.h include from NetDeviceController.hh

Socket: Add up(), down() and isUp() members to NetdeviceController
Utils/Daemon: Fix dup() bug
Utils/Daemon: Dump registered scheduler events on fork() WARNING

added some doc in DVBSocket

added more tests to increase test coverage