Partially silent options

[dzmitry.lahoda]

I use to mount my TC volumes with next command on Windows:
```
call getpsw
call truecrypt /volume "i:\1.tc" /letter "X" /auto /p %password% /silent /quit
call truecrypt /volume "i:\2.tc" /letter "V" /auto /p %password% /silent /quit
```

What is bad about it that `/silent` eats any errors even in case of wrong password, no volumes mounted.

If I do not use `/silent` TC window is shown for `1.tc` mount, I have to close it manually and then `2.tc` mount command is run.

Expected: Some '/silent-if-no-errors` command which is silent only if there where no errors on mount.

Actual:
Nothing happens when error, so I run my script again after checking available devices.

Possible:
Run without '/silent', improve `cmd` script to close window for `1.tc` or do not wait window to close before run `2.tc`command or check devices via script and retry. These are complicated and I am not here yet.