meeting url start

conf/client/clientMessages.properties

conf/server/controllersAndFamilies.properties

.../fr/ill/ics/client/control/experiment/ExperimentData.java

...ain/java/fr/ill/ics/client/view/factory/ImageFactory.java

src/main/resources/img/multiclient/Untitled.png

src/main/resources/img/multiclient/emptyBlueSquare.png

src/main/resources/img/multiclient/emptyOrangeSquare.png

src/main/resources/img/multiclient/livechat.png