* print.c (scm_print_state_vtable, print_state_pool):

* print.c (scm_print_state_vtable, print_state_pool):
Initialize.  These variables are now registered as gc roots.

(scm_current_pstate):  Update documentation.

(scm_current_pstate, scm_make_print_state, scm_free_print_state,
scm_prin1, scm_init_print):  print_state_pool is registered as a
gc root and thus does not need to be protected by a surrounding
pair any more.

(make_print_state):  The car of print_state_pool no longer holds
the scm_print_state_vtable.

(scm_current_pstate, scm_make_print_state, print_circref,
scm_iprin1, scm_prin1, scm_iprlist):  Prefer !SCM_<foo> over
SCM_N<foo>.

(scm_prin1):  When building lists, prefer scm_list_<n> over
scm_cons[2]?.

(scm_iprlist):  Removed a redundant SCM_IMP test.

(scm_simple_format):  Use SCM_EQ_P to compare SCM values.