support for localizable documentation. Refs: #88.
As proposed by Helmut Zinn in CPC 1.7 rc6 plus:

1. reuse of open documentation window for 'Info->Documentation' as in 'Info-> Repository',
2. window title of window opened by 'Info_>Dopcumentation' expanded to include full module name.

Signed-off-by: Josef Templ <josef.templ@gmail.com>