1. Add kw to the Makefiles
2. Implement the algorithms as defined in SP800-38F, and RFC 3394.

While the old name is explicit and aligned with the RFC, it's also very long,
so with the mbedtls_ prefix prepended we get a 31-char prefix to each
identifier, which quickly conflicts with our 80-column policy.

The new name is shorter, it's what a lot of people use when speaking about
that construction anyway, and hopefully should not introduce confusion at
it seems unlikely that variants other than 20/1305 be standardised in the
foreseeable future.

Fixes #1347

This commit updates the Visual Studio project file
`visualc/VS2010/mbedTLS.vcxproj` to add the newly
introduced `rsa_internal.h` and `rsa_internal.c`.

Contains additional project file, ecdh_curve25519.vcxproj, as well as fix
for intermediate files causing the warning MSB8028 with Visual Studio 2015.

Contains additional project file, ecdh_curve25519.vcxproj, as well as fix
for intermediate files causing the warning MSB8028 with Visual Studio 2015.

The library/net.c and its corresponding include/mbedtls/net.h file are
renamed to library/net_sockets.c and include/mbedtls/net_sockets.h
respectively. This is to avoid naming collisions in projects which also
have files with the common name 'net'.

The library/net.c and its corresponding include/mbedtls/net.h file are
renamed to library/net_sockets.c and include/mbedtls/net_sockets.h
respectively. This is to avoid naming collisions in projects which also
have files with the common name 'net'.

Changed for library and yotta module