Enhancements for MultiInputs:
 - a replace method can be specified
 - a data container for simplifying the use of MultiInputs
 - tidied up update method in the MultiInputConnector class
The MergeSignals and MergeSpectrums modules now use the new "replace method" functionality from the MultiInput
A rewrite of the FilterGenerator class.

API-Change: This commit changes the behaviour of the FilterGenerator class
Add a module that calculates an energy decay curve from a given impulse response
The announcements are now propagated even when an output is deactivated
The gauge has now functionality to be added to a status bar more easily.
A module for calculating the complex conjugate of a Spectrum
Bugfix: The averaging algorithm SumAndDivide works on a copy of the input data now
Bugfix: A toolbar's checkboxes for hiding and logarithmizing components are
updated now, when the plot's properties are changed by the program
The WindowGenerator-Class can now generate a Signal with both a raising and
a falling edge

API-Changes:
 - The method SetInterval has been replaced by the methods SetRaiseInterval
   and SetFallInterval
 - The method SetRaising has been removed
The SweepGenerator can now take an interval of sample indices, in which it
will sweep from the start to the stop frequency.
A new module for a regularized inversion of a Spectrum
Some updates and extensions for the RecordTransferFunction example:
 - API between GUI and SignalChain has been cleaned up a little bit
 - Fade-in and fade-out for the sweep
 - Deconvolution with a regularized inverted sweep
Merge branch 'current' into gh-pages
updated documentation