FEATURE - add some layer for connection between element

[PhilippeAccorsi]

It is very simple to make link between element but we can't use very well the color of link
For example: I want to make a link between element connected by Ethernet cable but also make a link to explain monitoring connection and another link for backup. At present, with all link visible in the same time, the view is very complicated.

Also, at present just the last link is visible when many link in same position.

With layer (just for link), we can define one infrastructure (server and other things) and define some layer for different kind of connection.

With this layer we can show same infra with different point of view:

• ethernet connection with color for each speed
• backup connection between server
• monitoring connection from diferent monitoring system
• etc.