Fix deref+port redo

[YruamaLairba]

hi, I reworked ports system to prevent having mutable reference to inplace output data I mentioned on #106

Notable change:

• InputPort,OutputPort and PortType system is replaced by just types that are the ports.
• There is now RCell and RwCell type used for inplace ports. RCell prevent is used to prevent writing through input port and RwCell is just here to be consistent with RCell
• ports are organized in 2 module, inplace for ports supporting inplace processing and, not_inplace for ports not supporting inplace processing.

Current state:

• i still need to update some plugin in docs folder
• atom crate still broken