Add in logic to parse BMP strings.

So the code can parse a certificate like this (and get the subject’s localityName):

-----BEGIN CERTIFICATE-----
MIIDlzCCAn+gAwIBAgIFAOVKIOkwDQYJKoZIhvcNAQEFBQAwZDEXMBUGA1UEAxMO
Y3BhbmVsZG9ncy5vcmcxCzAJBgNVBAsTAnVzMQswCQYDVQQGEwJISzELMAkGA1UE
ChMCdXMxCzAJBgNVBAgTAnR4MRUwEwYDVQQHHgwAcgBvAG0A4gBuAQMwHhcNMTMw
NzA5MTgzOTUxWhcNMTQwNzA5MTgzOTUxWjBkMRcwFQYDVQQDEw5jcGFuZWxkb2dz
Lm9yZzELMAkGA1UECxMCdXMxCzAJBgNVBAYTAkhLMQswCQYDVQQKEwJ1czELMAkG
A1UECBMCdHgxFTATBgNVBAceDAByAG8AbQDiAG4BAzCCASIwDQYJKoZIhvcNAQEB
BQADggEPADCCAQoCggEBAOAkLszkgXzz4eQ4/h0nsQh/0uYdxYutBCcwfsuP1q0u
6abbIlbweTH9/7FhFujF9MHdq72sNmuFIfCElNZ/ypBSU0A4agmQnF27ff6RIsPA
kDoPuGz0nR2eLG2wwYxsJbOkDfQgaHjIGDHPgmhEaWprYdvI5a5OnibWVQlbCxLv
tQ8VYCxLrzlefPzQ/2jSRsT+7ugMyeGQN+SNCezn2GbuSJMD7e/85LYjX+7ObF1h
ijrVFClE13KdU7RhsClaSJbsHCcevxMW7JLEWC15DC9Cid3VoZjcrQFLGR9/Gy0A
hgBHPHxcnnTUrQV5jBaJvRKpdXHbmt876hPMSArSX08CAwEAAaNQME4wHQYDVR0O
BBYEFHXNuzpFJxF1ftBQdbjGpsfXQ1r5MB8GA1UdIwQYMBaAFHXNuzpFJxF1ftBQ
dbjGpsfXQ1r5MAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQEFBQADggEBAAul8PIj
6wUZt46LeUtCCkB1duMpcnDJ4dIlESk+ronN7qWu5MgMRE8TGWLcHtTP9ZTegiB8
Bxv7IqfCvu/3v4kcGsOaqGnYLMlqV1EP4L+Zt6yBkk/GG5HdeFNRYUtaiPht9uJ5
0k1NNsJFZEE6QumZGEMGDg2ZoZrZqxzxIV2U38NA3fZFUoRvqs6wTevZMRnNbyCb
Tf8+l0G4sQdIKn2MtNQZKI7LYP2qHNjL9POVlfnnPHBnsW4iS7IeBSWAh40ZvKmZ
p/lQo7oRdCJ3DpYaxRgUmPv7pyWLvVkrRsgIBFL859WplwsG+JpkjIncTTtbNnqf
v04Z0l7rsXrbRJQ=
-----END CERTIFICATE-----