axis_text don't work

[fglueck]

I generate a BarAndLineGraph with

'structure'                 => [ 'key' => 'id',
                                       'value' => ['his', 'jvp', 'cur'],
                                       'axis_text' => 'wk_start',
                                       'colour' => ['c1', 'c3', 'c2', 'c4'],

In this case the "id"-Field is shown on axis.

[goat1000]

It doesn't appear to be working for multi-dataset graphs. I'll fix it.

[goat1000]

This should be fixed by 1e4eeb7