Merge pull request #15 from BSieglin/master

Added tBegin and tEnd to getSignal. Added missing docstrings and inserted some line breaks.
Merge pull request #16 from BSieglin/master

Added getSignalCalibrated which returns the calibrated signal.
Merge pull request #17 from BSieglin/master

Added getSignalGroup
Merge pull request #18 from BSieglin/master

Added check if signalGroup has proper shape.
Merge pull request #19 from BSieglin/master

Changed warnings and getSignal / Calibrated
Merge pull request #20 from BSieglin/master

Implemented __call__
Merge pull request #21 from BSieglin/master

Added getSignalGroupCalibrated
Merge pull request #22 from BSieglin/master

Added doc strings and dtype fail safes.
Merge pull request #23 from BSieglin/master

Reading character signalgroup.
Merge pull request #25 from BSieglin/master

Added parameter functionality
Added parameterSet to __call__

__call__ now returns the corresponding parameterSet using
getParameterSet. tBegin and tEnd are not used for this case.
Added getList.

getList returns the names of the objects in the specified list.
Merge https://github.com/pyIPP/pyddww
Added getMappingInfo

getMappingInfo returns the mapping info of a specified name in a
mappingInfo object.
getSignalGroupCalibrated missing timebase

getSignalGroupCalibrated now also handles signalgroups without timebase.
All getSignal, getSignalCalibrated, getSignalGroup and
getSignalGroupCalibrated now behave the same way.
Added GetSignal for backwards compatibility.

GetSignal(name, cal=False) combines getSignal, getSignalCalibrated,
getSignalGroupCalibrated and getSignalGroup.
Added signal class

The signal class is intended to be returned by __call__ if the object is
a signal. It contains the signal name, data and if available the time
and the unit.

For the class basic functionality has been implemented.

__call__(tBegin, tEnd) returns a signal class containing the signal in
the specified time interval.

max(), min() and median() have been implemented. In case of min and max
NaNs are ignored.

The Idea is:

sf = dd.shotfile('DCN', 29708)
H1 = a('H-1')
medianValue = H2(1.5, 1.6).median()
Added signalGroup, fix getSignalGroupCalibrated

Similar to signal the class signalGroup is implemented. It provides min,
max, mean and median. mean has also been implemented for signal.
For signalGroups min, max, mean and median have the keyword axis which
works like the axis keyword in numpy.

axis = None --> global min, max, mean, median
axis = 0,1,... --> min, max, mean, median along this axis
added usage tracking, ignoring .pyc files
Merge branch 'master' of https://github.com/pyIPP/pyddww