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()

Utils: Optimize ExceptionMixin implementation
Utils/Console: Add error logging to UDPServer

Utils/Console: Update completion to use new prefix return value
Utils/Console: Update completion to allow completing command arguments (i.e. help, ls, cd)
Utils/Console: Move auto-repeat-on-empty-return functionality into LineEditor keybinding
Utils/Termlib: Update completer documentation

Utils/Console: Add documentation to Client members
Utils/Console: Add support for std::pair parsing/formatting
Utils/Console: Some more documentation

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

Utils/Console: Repeat repeated command on console

Utils/Console: Implement special single-token argument parsing for program options (remove double quoting)

Utils/Console: Add 'lr' command

PPI: Documentation