Runs clang-tidy pass by ref across the codebase to fix-up various
warnings we are seeing in cppcheck

Also updated class_maker.py

They are very closely related and two objects cannot be attached
to the same canvas without causing complex interactions
between the zoom and pan modes. Combining them deals with
mode switching automatically.

Protects the python call with the GIL. This is required
in Python 3 to be able to access the object attributes.

Additional locks of the GIL are required to avoid an
invalid threadstate.

The true segfault fixes was acquiring the GIL for all
Python operations.
This reverts commit 6591c66e.

Use compatability macros for string conversion
Use six.next for Cycler iteration.

In the subplot case we need to create the figure outside
of the class and pass it to the canvas as matploltib does.
If this is not done then trying to retrieve the figure later
leads to accessing a dead object.

The mouse event handlers need to keep track of whether
a drag has occurred to correctly determine when to emit
a clickedAt signal.

The first entry in the vector was not deleted as expected
and also a vector was not the most sensible choice of container
given the frequent insertion/removal

When a detector is selected with a peak marker attached
to it we draw the HKL value on the miniplot. Required adding
methods to retrieve the axes scale limits to the Axes class.

Use text functionality to label peaks on the miniplot.

Adds a Zoomer object to the mplcpp library to adds
zooming capabilities to an existing canvas. This works
differently to the Qwt4 version and has a home button
to zoom out and leaves the right-click button to
exclusively control the context menu.

Added scale-type get/set methods to Axes to aid this.

The remove curve option has been implemented. It required
the introduction of a C++ wrapper for colorConverter to map
from matplotlib colors to a QColor.

Introduces the Cycler class to wrap cycler.Cycler from Python
and provide cycling of the stored curve colors. The curves
cannot yet be removed.

Use this to set the correct Axis scales in the miniplot

The scales are not yet being adjusted properly

Readability is improved along with the ability to sanity
validity of the arrays given to the miniplot.

MiniPlotMpl and Colorbar classes have introduced that have
a public to match their Qwt counterparts. Nothing yet functions.