Turns tie points into an adm object that represents an age-depth model
Details
by default, intervals with no sediment accumulation are marked as destructive.
tp_to_adm does not check whether the inputs define a valid age-depth model. For this, use
is_adm
See also
is_adm() to check validity of adm objects, get_T_tp() and get_L_tp() to extract time and height/length tie points
