use layer manager in Command

[anonymous]

The Command class should get the active layer from the layer manager. otherwise it does not seem possible to use the command in a test with JOSMTestRules, because "Main.main" is null.

package org.openstreetmap.josm.command:

/

• Creates a new command in the context of the current edit layer, if any */

public Command() {

this.layer = Main.main == null ? null : Main.main.getEditLayer();

}