Add some simple scripts for signing/flashing

These are some simple scripts for signing images (with an example with a
hardcoded path), a fixed root key that matches the one checked into the
code, and a few scripts to use the Segger debugger to flash the images.
diff --git a/scripts/newtimg.py b/scripts/newtimg.py
new file mode 100644
index 0000000..1e968d7
--- /dev/null
+++ b/scripts/newtimg.py
@@ -0,0 +1,67 @@
+# BOOT_IMG_MAGIC =                0x12344321
+BOOT_IMG_MAGIC = [ 0xf395c277, 0x7fefd260, 0x0f505235, 0x8079b62c ]
+IMAGE_MAGIC =			0x96f3b83c
+IMAGE_MAGIC_NONE =		0xffffffff
+
+#
+# Image header flags.
+#
+IMAGE_F_PIC =			0x00000001
+IMAGE_F_SHA256 =		0x00000002  # Image contains hash TLV
+IMAGE_F_PKCS15_RSA2048_SHA256 = 0x00000004  # PKCS15 w/RSA and SHA
+IMAGE_F_ECDSA224_SHA256 =	0x00000008  # ECD
+IMAGE_HEADER_SIZE =		32
+
+# Digest sizes
+SHA256_DIGEST_SIZE =		32
+
+# Signature sizes
+RSA_SIZE =                      256
+ECDSA_SIZE =                    68
+
+# 
+# Image trailer TLV types.
+# 
+IMAGE_TLV_SHA256 =		1   # SHA256 of image hdr and body
+IMAGE_TLV_RSA2048 =		2   # RSA2048 of hash output
+IMAGE_TLV_ECDSA224 =		3   # ECDSA of hash output
+
+
+OFFSET_VECTOR_TABLE = 0x20
+OFFSET_IH_MAGIC = 0
+OFFSET_IH_TLV_SIZE = 4
+OFFSET_IH_KEY_ID = 6
+OFFSET_IH_PAD1 = 7
+OFFSET_IH_HDR_SIZE = 8
+OFFSET_IH_PAD2 = 10
+OFFSET_IH_IMG_SIZE = 12
+OFFSET_IH_FLAGS = 16
+OFFSET_IH_VER_MAJOR = 20
+OFFSET_IH_VER_MINOR = 21
+OFFSET_IH_REVISION = 22
+OFFSET_IH_BUILD_NUM = 24
+OFFSET_IH_PAD3 = 28
+#struct image_version { uint8_t iv_major; uint8_t iv_minor; uint16_t iv_revision;
+#    uint32_t iv_build_num;
+#};
+#
+#/** Image header.  All fields are in little endian byte order. */
+#struct image_header {
+#    uint32_t ih_magic;
+#    uint16_t ih_tlv_size; /* Trailing TLVs */
+#    uint8_t  ih_key_id;
+#    uint8_t  _pad1;
+#    uint16_t ih_hdr_size;
+#    uint16_t _pad2;
+#    uint32_t ih_img_size; /* Does not include header. */
+#    uint32_t ih_flags;
+#    struct image_version ih_ver;
+#    uint32_t _pad3;
+#};
+#
+#/** Image trailer TLV format. All fields in little endian. */
+#struct image_tlv {
+#    uint8_t  it_type;
+#    uint8_t  _pad;
+#    uint16_t it_len;
+#};