PPI: Allow access to source/sink helper in (Active|Passive)Socket(Source|Sink)

Small SCons V0.96 compatibility fix

PPI: Fix cloneSource unit-test packet construction
Scheduler: BUGFIX: uninitialized loop variable
Scheduler: BUGFIX: delay deletions in fdTable_ (can't change map while iterating over it)
Add global 'valgrind' target
Add 'valgrind.sup' suppressions file to suppress custom benign valgrind errors
Fix all unit-tests to run correcly under valgrind (mostly timing adjustments)

Scheduler: Simplify callback parameter (remove mostly ignored callback handle parameter)
Scheduler: Add timeoutEarly and timeoutAdjust parameters

Utils: Rename SafeBool to safe_bool (hmm ...)

Logger: Implemented compile-time configuration support

Fix dependency generation for built programs
Fix depenfencies for auto-generated sources

Add 'fixlinks' target and add 'fixlinks' to the auto-build
PPI: exchange registerEvent arguments
PPI: Add connector 'operator()' aliases
PPI: More detailed 'route' and 'registerEvent' documentation

Fix TAGFILE dependencies
Fix some URL references
PPI: Add additional 'route' documentation
Globally disable SUBGROUPING in Doxygile.global

Make all include path's relative
Add 'senf/Packets.hh', 'senf/PPI.hh' and 'senf/Socket.hh'

Utils: Implement mpl.hh metaprogramming helpers

Socket/Protocols/Inet: Remove not implemented  async resolv constructors (in favor of a later non-member implementation)
Socket/Protocols/Inet: More detailed exceptions thrown by INet4Address / INet6Address

Examples/RateStuffer: Use CloneSource module
Exmaples/RateStuffer: Implement using a RateStuffer subnet
PPI: Implement CloneSource
PPI: Add throttle()/unthrottle() to passive debug modules
PPI: Implement DiscardSink
PPI: Implement ThrottleBarrier
PPI: Implement missing unit tests
PPI: Complete the documentation
Scheduler: Improve ClockService performance and remove a race condition
Scheduler: Clean up Scheduler::process()
Utils: Make singleton::instance() protected by default and fix implementation
Remove private members from doxygen documentation

PPI: Add documentation
Utils: Make Logger macros define empty stub types

PPI: Implement ActiveFeederSource and ActiveFeederSink debug composites

PPI: More documentation
PPI: Implement IdleEvent and ActiveFeeder
PPI: add Module::running() member
Scheduler: Remove MinTimeout (not needed with ClockService working)

Scheduler: Implement ClockService clockSkew detection / fixup

Examples/RateStuffer: documentation

PPI: Implement IntervalTimer event
Scheduler: Change timeout() argyument to absolute time represented as ClockService::clock_type
Scheduler: Implement timer event cancelation
PPI: Implement RateStuffer in ppitest

Packets: Silence PacketRegistry warnings with final=1
Utils: Remove MicroTime
Scheduler: Sart implementing more reliable timing mechanism

PPI: Add additional unit testing

PPI: Add boolean test for debug modules

PPI: Fix PassivePackeSink: provide front() instead of back() members
PPI: Provide specializations for void-argument callbacks in Events and Route
PPI: Add notifyThrottle/notifyUnthrottle to EventDescriptor
PPI: Re-implement routing classes using a traits-based implementation
PPI: Add Route unit testing (mainly testing throttling)

PPI: Implement throttling
PPI: Implement ModuleManager and ppi::init
PPI: Implement ThresholdQueuing
PPI: Hugely extended routing classes

PPI: Add RateStuffer image to documentation