refactor kexdh code a bit, start working on ecdh etc

--HG--
branch : ecc
more bits on ecc branch

--HG--
branch : ecc
ecc key import function

--HG--
branch : ecc
Set LTC_SOURCE for proper ltm_desc etc

--HG--
branch : ecc
More changes for KEX and ECDH. Set up hash descriptors, make ECC code work,
ses.hash and ses.session_id are now buffers (doesn't compile)

--HG--
branch : ecc
Make _sign and _verify functions take a buffer* rather than void* and int

--HG--
branch : ecc
ecc kind of works, needs fixing/testing

--HG--
branch : ecc
- Fix various hardcoded uses of SHA1
- rename curves to nistp256 etc
- fix svr-auth.c TRACE problem

--HG--
branch : ecc
ecdh works against OpenSSH

--HG--
branch : ecc
add printmpint() for debugging

--HG--
branch : ecc
- Rename buf_put_ecc_pubkey_string() to buf_put_ecc_raw_pubkey_string()
- Reindent ecc.c properly

--HG--
branch : ecc
start on ecdsa keys

--HG--
branch : ecc
Be safer with how we handle ltc_ecc_sets[] (particularly with
system libtomcrypt)

A bit of progress with ecdsa code

--HG--
branch : ecc
A bit of debugging output

--HG--
branch : ecc
A bit of work on ecdsa for host/auth keys

--HG--
branch : ecc
more ecdsa signkey work, not correct

--HG--
branch : ecc
ecdsa is working

--HG--
branch : ecc
Fix ecdsa verification

--HG--
branch : ecc
Fix build for dropbearkey and ecdsa with certain options

--HG--
branch : ecc
merge

--HG--
branch : ecc