Replace bios with bootloader, don't use bootsector

Instead of using the bootsector to load a bootloader, just put the
bootloader in the ROM and call it a day. It looks for a file on the SD
card in the root directory named `kernel.bin` and loads it into memory.

This is not a perfect solution, as the kernel will grow larger and the
kernel load address will have to change. At this point I could add back
the bootloader, but that is for later.

Also the bootloader is just a copy of the kernel, so that can be trimmed
down a lot.

sw/bootloader/filesystem/o65.h

@@ -0,0 +1,65 @@
+#ifndef _O65_H
+#define _O65_H
+
+#include <stdint.h>
+
+#define O65_NON_C64 0x0001
+#define O65_MAGIC_0 0x6f
+#define O65_MAGIC_1 0x36
+#define O65_MAGIC_2 0x35
+
+#define O65_OPT_FILENAME 0
+#define O65_OPT_OS 1
+#define O65_OPT_ASSEMBLER 2
+#define O65_OPT_AUTHOR 3
+#define O65_OPT_DATE 4
+
+#define O65_OS_OSA65 1
+#define O65_OS_LUNIX 2
+#define O65_OS_CC65 3
+#define O65_OS_OPENCBM 4
+#define O65_OS_SUPER6502 5
+
+typedef union {
+    struct {
+        int cpu : 1;
+        int reloc : 1;
+        int size : 1;
+        int obj : 1;
+        int simple : 1;
+        int chain : 1;
+        int bsszero : 1;
+        int cpu2 : 4;
+        int align : 2;
+    };
+    uint16_t _mode;
+} o65_mode_t;
+
+typedef struct {
+    uint16_t c64_marker;
+    uint8_t magic[3];
+    uint8_t version;
+
+    o65_mode_t mode;
+
+    uint16_t tbase;
+    uint16_t tlen;
+    uint16_t dbase;
+    uint16_t dlen;
+    uint16_t bbase;
+    uint16_t blen;
+    uint16_t zbase;
+    uint16_t zlen;
+    uint16_t stack;
+
+} o65_header_t;
+
+typedef struct {
+    uint8_t olen;
+    uint8_t type;
+    uint8_t data[1];    //This is actually variable length
+} o65_opt_t;
+
+void o65_print_option(o65_opt_t* opt);
+
+#endif