Add bash completion for dynamic compiler formats

This is half a joke and half serious. If we brainstorm a little, maybe we find out it's actually possible.

It would be very cool to

$ ../run/john -test -form:dynamic='<TAB><TAB>

and get

$ ../run/john -test -form:dynamic='
gost  haval128_3  haval128_4  haval128_5  haval160_3  haval160_4  haval160_5  
haval192_3  haval192_4  haval192_5  haval224_3  haval224_4  haval224_5  
haval256_3  haval256_4  haval256_5  keccak_256  keccak_512  md2  md4  md5  
panama  peoplesoft,  ripemd128  ripemd160  ripemd256  ripemd320  sha1  sha224  
sha256  sha384  sha3_224  sha3_256  sha3_384  sha3_512  sha512  skein224  
skein256  skein384  skein512  tiger  whirlpool
$ ../run/john -test -form:dynamic='_

and so on

$ ../run/john -test -form:dynamic='sha<TAB><TAB>
sha1  sha224  sha256  sha384  sha3_224  sha3_256  sha3_384  sha3_512  sha512
$ ../run/john -test -form:dynamic='sha_

As always with bash completion, it's not so much about saving a keypress. It's about listing the alternatives in a super convenient way.

I'm a bit worried the (mandatory) single-quote makes it harder though. Not that I have any other source for my worries than gut feeling.