$term->FeaturesReturns a reference to a hash whose keys are features present in the
current implementation and whose values are those assigned to each
feature. Several optional features are used in the
minimal interface: appname should be present if the first argument
to new is recognized, and minline should be present if
MinLine method is not a dummy. autohistory
should be present if
lines are put into history automatically (maybe subject to
MinLine), and addhistory if the addhistory method
is not a dummy.