Revert "remove readout of colorbar's xaxis options"

This reverts commit 448b804dc642b977474e2ef5f5ce438187fd56e1.
Add new testcase for colorbar

R2014b handles colorbars smart:  `XLabel` and `YLabel` merged into `Label`
Use colormap 'jet' to create comparable output with MATLAB R2014b
* Check horizontal/vertical colorbar (subplots)
* Check if 'direction' is respected
* Check if multiline label and title works
* Check if latex interpreter works in label and title
add function `isHG2` that returns graphic system
fix multiline colorbar title
Handle colorbar differently in HG2 graphics system

MATLAB R2014b introduced an new graphics system. It is object oriented and changed some behavior. For example colorbars are now not treated as axes objects any longer.

For exmpale, now there is only one 'label' for the whole colorbar and one 'direction' setting.
add TODOs