[TimeVaryingDCMPlanner] restructure of setDCMReference() and setContactPhaseList()

[GiulioRomualdi]

#208 implements setDCMReference() however the user had to call the function after setContactPhaseList(). Thanks to this PR, setDCMReference() does not depends on setContactPhaseList() and the user can call it whenever their want.

cc @paolo-viceconte

[prashanthr05]

Ok for me! But I would wait for @S-Dafarra approval as well.

[S-Dafarra]

Just a simple suggestion. So basically, you can set the initial dcm condition without changing the foot list, right?

[S-Dafarra]

Maybe we can add some tags to distinguish between errors and info messages.

[GiulioRomualdi]

I would do it in a separate PR for all the error/warning/info in the repo. Indeed now all the errors/warnings/info are printed with cerr and there is not a common function to call. #137 (comment)

[GiulioRomualdi]

For instance, we can use something like this: https://github.com/robotology/idyntree/blob/2e5cf7180a517bf91777d48761c4c12c94e7e404/src/core/include/iDynTree/Core/Utils.h#L66-L93

[S-Dafarra]

I was not referring to cerr but rather to the message itself. It is not clear whether the message is an error or not. I was suggesting adding something like [ERROR] since it is going to be much easier to find them in the middle of tons of other messages.

[GiulioRomualdi]

On that one I agree. Done in 7999c2f

[GiulioRomualdi]

So basically, you can set the initial dcm condition without changing the foot list, right?

This possibility was already implemented in the first version. With this PR the user can set the reference dcm (used for regularization) independently from the foot list

[GiulioRomualdi]

Comment #220 (comment) updated. @S-Dafarra