fix locale support

[szabgab]

Make sure we have the right menu options based on the available translation files (and existing locale support of the host system).

Allow the user to switch between languages and set one that will be the default for next time. The user should be able to select between
the languages we provide or "system language" that is the current locale or English if we don't support the current locale.

[szabgab]

At least on linux

 $ locale 

shows the current locale settings

 export LANG=he_IL.UTF-8

sets the locale (in the above case to Hebrew)

 $ perl -MWx -le '$n = Wx::Locale::GetSystemLanguage(); $w = Wx::Locale->new($n); printf("$n %s\n", $w->GetCanonicalName); '

prints out what Wx thinks what is the system languages (based on the locale setting) and prints out the name of the locale.

 $ perl -MWx -le '$n = 58; $w = Wx::Locale->new($n); printf("$n %s\n", $w->GetCanonicalName); '

prints out the name of locale 58 (that happens to be en_US)