Move type operations to another structure

Every type has free, print, check_constraints, ber_decoder, der_encoder,
xer_decoder, xer_encoder, uper_decoder, uper_encoder and outmost_tag
operations. We move them out to a separate structure asn_TYPE_operation_t.

Combined with previous logic simplification, these operations are based
on ASN.1 basic types, constructed types and string types. So we can
reduce the space occupied by asn_TYPE_descriptor_t variables.
diff --git a/skeletons/tests/check-OER-INTEGER.c b/skeletons/tests/check-OER-INTEGER.c
index ca35823..91a9f1e 100644
--- a/skeletons/tests/check-OER-INTEGER.c
+++ b/skeletons/tests/check-OER-INTEGER.c
@@ -40,7 +40,7 @@
 
     (void)dummy;
 
-    ret = asn_DEF_INTEGER.oer_decoder(0, &asn_DEF_INTEGER, constraints,
+    ret = asn_DEF_INTEGER.op->oer_decoder(0, &asn_DEF_INTEGER, constraints,
                                       (void **)&st, buf, size);
     if(ret.code != RC_OK) {
         /* Basic OER decode does not work */
@@ -124,7 +124,7 @@
 
     dump_data(lineno, tmpbuf, tmpbuf_size);
 
-    ret = asn_DEF_INTEGER.oer_decoder(0, &asn_DEF_INTEGER, constraints,
+    ret = asn_DEF_INTEGER.op->oer_decoder(0, &asn_DEF_INTEGER, constraints,
                                       (void **)&stIn, tmpbuf, tmpbuf_size);
     if(ret.code != RC_OK) {
         /* Basic OER decode does not work */