// This class corresponds to a time step (dt,it) of a field
// It contains the time step (dt) and the corresponding time value
// It also contains methods for selecting or unselecting this time step and it hold the name of the supporting mesh.
// This class corresponds to a time step (dt,it) of a field
// It contains the time step (dt) and the corresponding time value
// It also contains methods for selecting or unselecting this time step and it hold the name of the supporting mesh.