Initial balance : add possibility to edit text labels, add option to not plot IB additional levels until IB is finished

I've added fields to the initial balance indicator to select the text for each level.

I think this would be useful to many users, and if I've managed to do it, it's not complicated ^^.

You could add font selection too.
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I'd also like the levels to be plotted only when the initial balance period is over, to make the graph easier to read.

Typically when we put the vwap with standard deviations and the initial balance, all the lines overlap and it's very difficult to see clearly.