Adding test for TaskConfig build methods.
Fixing taskeditor to request all views at once rather than independently for each task. Fix error in base tasks.
Refactor InstrUser to get a callable rather than a command id. Avoid the declaration of command which should not exist.
Slight modification of the InstrManager.

InstrManager now returns a bool and dict/list for all request. The bool indicates whether the manager satisfied the request. If it did the dict contains the result otherwise otherwise a list containing the missing values is returned.
Add a default_header member to RootTask.
Begining of the refactoring of the measurement package.

Introducing the the plugin architecture and removing a lot of stuff which will move to their own packages.
Introducing the measurement/engines package.

Engines will be contyributed as extensions and will be responsible for performing measure. By default a ProcessEngine similar to the old system will be implemented.
Introducing the measurement/monitors package.

Monitors will now be provided as extensions (allow for multiple monitors). The defaiult system will be reimplemented using preferences.
Introducing measurement/headers, measurement/checks.

Two other extensions packages for contributing additional checks and headers factories.