core: move new object system to core module

this will allow a wider range of data structures (e.g. b_error, b_stream, b_stringstream) to make use
of the new object system, and other modules and library users can use the object system without
depending on the blue-object or blue-ds modules.

blue-ds will become a simple library of data structures (string, hashmap, etc), built on top of the
core object system.

core/class.c

@@ -0,0 +1,49 @@
+#include "class.h"
+
+#include "type.h"
+
+#include <blue/core/class.h>
+#include <stdlib.h>
+#include <string.h>
+
+void *z__b_class_get_interface(struct _b_class *c, const union b_type *id)
+{
+	const struct b_type_registration *type_reg = c->c_type;
+	struct b_type_component *comp
+		= b_type_get_component(&type_reg->r_components, id);
+
+	if (!comp) {
+		return NULL;
+	}
+
+	return (char *)c + comp->c_class_data_offset;
+}
+
+b_result b_class_instantiate(
+	struct b_type_registration *type, struct _b_class **out_class)
+{
+	struct _b_class *out = malloc(type->r_class_size);
+	if (!out) {
+		return B_RESULT_ERR(NO_MEMORY);
+	}
+
+	memset(out, 0x0, type->r_class_size);
+
+	out->c_magic = B_CLASS_MAGIC;
+	out->c_type = type;
+
+	b_queue_iterator q_it;
+	b_queue_foreach (&q_it, &type->r_class_hierarchy) {
+		struct b_type_component *comp
+			= b_unbox(struct b_type_component, q_it.entry, c_entry);
+		const struct b_type_info *class_info = comp->c_type->r_info;
+		void *class_data = (char *)out + comp->c_class_data_offset;
+
+		if (class_info->t_class_init) {
+			class_info->t_class_init(out, class_data);
+		}
+	}
+
+	*out_class = out;
+	return B_RESULT_SUCCESS;
+}