important: node reorganization

[phoddie]

We've made some changes to the organization of the nodes directory. The primary motivation for the changes is to better support the MCU plugin by providing a more consistent organization. We took the opportunity to move from a flat list of nodes to a hierarchical collection which should be more convenient in the long run.

You should not need to make any changes to your flows. If you are using the MCU nodes (sensor, etc). you will need to uninstall the previous version and install the new one. The instructions are here.

The changes include a couple of work-in-progress features that were requested by developers working with Node-RED MCU Edition: invert checkbox for Digital In and Digital Out nodes and the ability to use a hex value (0x12) for I²C commands. These will be completed in the coming days.