changes and fixes for post-Grasshopper 0.9.61 full compatibility.

Includes:

Grasshopper.dll is automatically added as a reference for scripting
addition and removal of Inputs and Outputs is supported in the native Grasshopper ZUI way
code input and out output stopped working. This is fixed
code input and out output are now removable also via + and - ZUI signs
several IO issues in deprecated (old) components were fixed. Also old components should keep on working properly
GH_IO.dll deprecated iteration over chunks was removed
registration of input parameters now via the Grasshopper SDK-suggested way
floating editor could remain linked to a deleted component. This is fixed

mcneel / ghpython