Update on plugins: doc and co. Still to implement: custom commands

doc/dev_infrastructure/ttool_development_infrastructure.tex

...luginGraphicalComponent/CustomizerGraphicalComponent.java

src/main/java/cli/Interpreter.java

src/main/java/cli/PluginAction.java

src/main/java/myutil/Plugin.java

src/main/java/myutil/PluginManager.java