[REVIEW-3-5] fdo#50509 MSI: UI language selection from command line (e.g. silent install)

Hi,

Originally silent install installed all 100+ languages and it made the
installation slow. For 3.5.4 it was solved by running the language
pre-selection custom action not only during normal install, but during
silent install, too. Unfortunately it caused another problem, because
now users of silent install do not have the opportunity to select UI
languages, they always get what the SelectLanguage custom action
selects for them, i.e. the languages of the operating system.

Here comes the solution. If the UI_LANGS property is set, the language
guessing heuristic is switched off, and user can define explicitely,
what languages should be installed.

E.g.:
msiexec /i LibO_...._.msi UI_LANGS=en_US,de,fr,hu
It will install English (US), German, French, and Hungarian. There are
still some minor issues with language selection, because for example
pt_BR also selects pt implicitely, but this is the same what we have
with automatic language selection.

When the user tries to fool the installer by giving invalid language
codes, installer will fall back to en_US. Also, en_US is not installed
by default, unlike with the automatic selection. I tried the patch
with a limited set of languages (10), and it worked well. Please
review the patch for 3.5 (better to ignore whitespace changes, when
you view the patch).

http://cgit.freedesktop.org/libreoffice/core/commit/?id=a77d16835504b4f82b6b9e59c213eea8a879219c

Thanks,
Andras