Merge remote-tracking branch 'origin/pr/108'

* origin/pr/108:
  add --default-key to allowed options

Pull request description:

i have no idea what i'm doing, but this is what i think mamarek proposed in #107 (comment)

Author: marmarek

src/gpg-common.h

@@ -29,6 +29,7 @@ enum {
     opt_command_fd,
     opt_comment,
     opt_compress_algo,
+    opt_default_key,
     opt_default_recipient,
     opt_default_recipient_self,
     opt_digest_algo,
@@ -143,6 +144,7 @@ static const int gpg_allowed_options[] = {
     opt_clear_sign,
     opt_comment,
     opt_compress_algo,
+    opt_default_key,
     opt_default_recipient_self,
     opt_digest_algo,
     opt_emit_version,
@@ -259,6 +261,7 @@ static const struct option gpg_long_options[] = {
     {"comment", 1, 0, opt_comment},
     {"compress-algo", 1, 0, opt_compress_algo},
     {"decrypt", 0, 0, 'd'},
+    {"default-key", 1, 0, opt_default_key},
     {"default-recipient", 1, 0, opt_default_recipient},
     {"default-recipient-self", 0, 0, opt_default_recipient_self},
     {"detach-sign", 0, 0, 'b'},