Add vim style exec

Thanks to bashseb for the patch.

Closes: #423
Signed-off-by: Sebastian Ramacher <sebastian+dev@ramacher.at>

commands.c

@@ -524,8 +524,14 @@ cmd_exec(girara_session_t* session, girara_list_t* argument_list)
 
     GIRARA_LIST_FOREACH(argument_list, char*, iter, value)
       char* r = girara_replace_substring(value, "$FILE", path);
+
       if (r != NULL) {
-      girara_list_iterator_set(iter, r);
+        char* s = girara_replace_substring(r, "%", path);
+        g_free(r);
+
+        if (s != NULL) {
+          girara_list_iterator_set(iter, s);
+        }
       }
     GIRARA_LIST_FOREACH_END(argument_list, char*, iter, value);
   }

config.c

@@ -422,6 +422,7 @@ config_load_default(zathura_t* zathura)
   girara_inputbar_command_add(gsession, "close",      NULL,   cmd_close,           NULL,         _("Close current file"));
   girara_inputbar_command_add(gsession, "info",       NULL,   cmd_info,            NULL,         _("Show file information"));
   girara_inputbar_command_add(gsession, "exec",       NULL,   cmd_exec,            NULL,         _("Execute a command"));
+  girara_inputbar_command_add(gsession, "!",          NULL,   cmd_exec,            NULL,         _("Execute a command")); /* like vim */
   girara_inputbar_command_add(gsession, "help",       NULL,   cmd_help,            NULL,         _("Show help"));
   girara_inputbar_command_add(gsession, "open",       "o",    cmd_open,            cc_open,      _("Open document"));
   girara_inputbar_command_add(gsession, "quit",       "q",    cmd_quit,            NULL,         _("Close zathura"));