analysed barchart sample names are not in order

[teese]

In one example, after collecting data from multiple experiments:

• the bar chart showed the wrong sample names on the x-axis, BUT
• the scatter plot with a point for each experiment was good
• the saved excel and csv were both correct

Need to check if the bug can be repeated, and find how the sample names became unordered.

[teese]

fixed
added a much simpler barchart based on df.plot(kind="bar)