Build and test the new crypto toys

Build and test the new crypto toys

  * Add a collection of test programs.  (The upstream test programs are
    too heavily entangled with infrastructure that I'd actually prefer
    to replace with something like this new stuff.)

  * Add some new features to the header files `unaligned.h' and `u64.h'
    that are needed by the new code.

  * Almost all of Catacomb's crypto code depends on a header called
    <mLib/bits.h> which does various low-level bit operations.  Provide
    a fake version, `fake-mLib-bits.h', which implements the necessary
    things in terms of C99 <stdint.h> and what we already have lying
    around here in `unaligned.h' and `u64.h'.

With that, we have enough to build and run the tests and watch them all
pass.

Signed-off-by: Mark Wooding <mdw@distorted.org.uk>