Experiment configurator block order could be improved

Currently, our experiment configurator uses the block order to determine the setup order in the configuration page. This not always translates to a reasonable organisation of the blocks. For example, if the user starts drawing on the right of the page, then the first blocks on the configuration page would be the last ones in the dataflow order. An uninformed user could find this particularly counter-intuitive.

This can be fixed in two ways:

1. We allow the user to setup the "configuration" order by introducing some property that one can set while drawing the toolchain, or

2. We try to devise what is the best order by looking at the "x" (ordinate) position of the block.