RapidLib thread issues

[mzed]

Currently, RapidLib train() and run() methods aren't threadsafe. Some proposed fixes:

• train() should block run() This will be a quick update, so that run with throw an error if training is in progress
• run() for kNN can easily be improved. There are a couple of calculation variables that are part of the class but really don't need to be.
• run() for neural networks uses some memory. It's good that this doesn't need to be reallocated during training. There needs to be a new, threadsafe run method.
• run() for DTW ...maybe only allCosts is the problem? I should double-check this.

[mzed]

@samswain All these run methods are running on a reference to some input data object that is outside of the model. So, if that object changes then the results are going to be off. That should probably be passed by value, instead.

[sam-apparance]

The plugin can run these in the background, but makes sure it's only possible to run one at a time for now.

[mzed]

Can you pass data by value? If not, I can have a look. This week.

[mzed]

I think all of the other changes were made a year ago. Not at my computer

[sam-apparance]

Don't worry, I was just tying up this loose end a little. For now we work around the thread-safety issue.