Remove unncessary assert.

It was possible that when deleting elements the selection becomes invalid. That
resulted in the assert being caused on occasion. There's no need for the assert,
it could very easily just become a filtering mechanism to ensure the new
selection is still valid. This patch fixes that.

Change-Id: I3c48f94c3c7c312cbd534df03a20292ef6211b20
Fixed clang -Wloop-analysis warning

warning: variable 'i' is incremented both in the loop header and in the loop body [-Wloop-analysis]

The loop is indeed suspect, likely incrementing i too much.

Change-Id: I853aaac44ebf01ae734d8bd3369269ea58d571b7
Added code to deal with rendering double precision data

This uses an approach where the axes retain double precision data, and
coordinate with the vtkChartXY and vtkPlotPoints classes to scale the
data appropriately. This required some refactoring of the code dealing
with calculating the bounds and arranging the data ready for being
rendered. Functions that modify the plot transforms required some
enhancement to use the scaling factors when necessary.

Change-Id: Ic084d9dab7f02ded82187bd6207a3f837fef03ec
Added a test exercising the rendering of tiny numbers

Change-Id: I34ebfd9381302754da3ef808748b34dbdcabf8cc
Merge topic 'fix_unnecessary_assert' into master

953a5979 Remove unncessary assert.
Merge topic 'charts-double-precision' into master

082acecc Added a test exercising the rendering of tiny numbers
01a26ade Added code to deal with rendering double precision data
Merge topic 'Wloop-analysis' into master

a3dee773 Fixed clang -Wloop-analysis warning