Handle LABEL

[taorepoara]

What should be done

Implement LABEL command in the global Dofigen config scope.

Technical recommandation

Add a label field in the Dofigen struct of type HashMap<String, String>.

Implement the generation of the single line LABEL command from the previous field.

Is this task linked with any other ?

Defining the author label should be a good practice: #252

_{Huly®: DOFIG-248}