Here it is the solution in order to add the 'open terminal here' into the context menu of Elementary OS' file manager (generically called 'Files' - the executable is pantheon-files). For that ...
I know this is to be done by creating a .contractor file in /usr/share/contractor. For example, one like this will add a menu option to open a folder as root. [Contractor Entry] Name=Open folder as ...
Example: I press Supper button: menu opens. I write "fir": it shows Firefox, just like any launcher. I press Enter, it starts searching the whole system for files named "fir". I can avoid this by ...