* When downloading a signed message, and processing it, we use

   * When downloading a signed message, and processing it, we use
     body->nested.part instead of b->nested.part in the
     do_detached_signature_verify function, and save its body and mime
     headers in create_local_cache. Now all signed messages should
     verify correctly.

   * Protect against potential crash bug in write_passfile function by
     checking if text != NULL. text can only be null if there are no
     passwords to save. We assume we could get write_passfile called
     with null arguments, so this is just to protect that.

   * Add handling of corner cases to several functions by initializing some
     variables. Reported and patched by James Jerkins.

   * When selecting the certificate/key pair to encrypt/decrypt the password
     file choose it in this order:
	- if -pwdcertdir is given look for certificates there, if nothing
	  there, we bail out;
	- otherwise we look in the default directory, if anything there
	  and it matches to be a key/cert pair, we use it;
	- otherwise we check if smime_init() has been called. If not
	  we call it;
	- we check if a key/cert pair has been found with smime initialized,
	  if so, use it and copy it to the default directory;
	- if not, check if there is anything in the default smime directories
	  (.alpine-smime/private and .alpine-smime/public), and in this
	  case copy it to the default.
	- otherwise we bail. We will eventually create a certificate/key
	  pair for the user;
	- finally, if we called smime_init(), we call smime_deinit().

	Throughout this process, if smime_init() was not called before
	we tried to get the cert/key pair we exit this process without
	ps_global->smime->inited set, so that other process that need
	to call smime_init() get the right structure initialized. This is
	done because we might pick a cert/key pair to decrypt the password
	file.