Rewrote crt0, init, and chainloading code

start.s, init.c, linker.ld and linker.specs are meant
to be re-used by user applications, should they remove the defines
from init.c and the .chainloader* sections from the linker script

fusee/fusee-primary/src/chainloader.h

@@ -0,0 +1,25 @@
+#ifndef FUSEE_CHAINLOADER_H
+#define FUSEE_CHAINLOADER_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define CHAINLOADER_ARG_DATA_MAX_SIZE 0x6200
+#define CHAINLOADER_MAX_ENTRIES       128
+
+typedef struct chainloader_entry_t {
+    uintptr_t load_address;
+    uintptr_t src_address;
+    size_t size;
+    size_t num;
+} chainloader_entry_t;
+
+extern chainloader_entry_t g_chainloader_entries[CHAINLOADER_MAX_ENTRIES]; /* keep them sorted */
+extern size_t g_chainloader_num_entries;
+extern uintptr_t g_chainloader_entrypoint;
+
+extern char g_chainloader_arg_data[CHAINLOADER_ARG_DATA_MAX_SIZE];
+
+void relocate_and_chainload(int argc);
+
+#endif