Add a None option in CustomDrawers

[marc-antoine-girard]

Description

When we set a SerializableInterface to an instance of something, there is no where to simply deassign it.

Unity always add a None in its selectors like so:

It would be nice to have the same thing (watch out for my paint skillz)

Issue Type:

• QOL

Note

• Adding this feature would require to update the Documentation (Readme.md)