Fixes: - react on build/ run configuration changes
- now notices environment changes, like switching Qt versions
- start button is now only shown if we have a valid qemu runtime
- enabled/ disabled state works properly when loading a project
Task-number: QTCREATOR-210, QTCREATORBUG-1252, QTCREATORBUG-1082
Reviewed-by: ck
* Use id() for methods returning a string used to represent
some type of object.
* Use displayName() for strings that are meant to be user
visible.
* Quieten some warnings while touching the files anyway.
* Move Factories to their products in the plugins where that
was not done before.
Reviewed-by: dt
