Adding in dev infra document information on the XML format used by TTool to save models

doc/dev_infrastructure/ttool_development_infrastructure.tex

src/main/java/tmltranslator/toproverif/TML2ProVerif.java

src/main/java/ui/MainGUI.java

src/main/java/ui/avatarsmd/AvatarSMDSendSignal.java

src/main/java/ui/window/JDialogAvatarSignal.java