Add a PreExecutionHook querying the user to check some parameters

[MatthieuDartiailh]

The idea is that in some cases it may be best to manually check that some stuff is properly set before running the measurement and the system may not be able to asses it (such as putting a cover on a window). The hook should accept a list of question to ask and be able to nicely timeout (settable) in case the user is not there to perform the check. The user should be able to choose whether to abort or continue in case of a time out. A two dialog system the first one checking the user availability and second asking the question (this way the user can take its time to run the checks).