Restore Finnish translations

From what I have tested, the translation is now more sensible than the
previous machine and human translation mix.

Some translations were intentionally left empty, either because they
made no sense to translate, or if I didn't know what a reasonable
translation would be.

Includes previous translations from ts-korhonen and ziplantil, as well
as probably still some machine translations that were valid.

src/qt/qt_progsettings.cpp

@@ -54,6 +54,7 @@ QVector<QPair<QString, QString>> ProgSettings::languages = {
     { "de-DE",  "German (Germany)"         },
     { "en-GB",  "English (United Kingdom)" },
     { "en-US",  "English (United States)"  },
+    { "fi-FI",  "Finnish (Finland)"        },
     { "fr-FR",  "French (France)"          },
     { "it-IT",  "Italian (Italy)"          },
     { "ja-JP",  "Japanese (Japan)"         },

src/qt/qt_translations.qrc.in

@@ -5,6 +5,7 @@
         <file>86box_en-US.qm</file>
         <file>86box_en-GB.qm</file>
         <file>86box_es-ES.qm</file>
+        <file>86box_fi-FI.qm</file>
         <file>86box_fr-FR.qm</file>
         <file>86box_hr-HR.qm</file>
         <file>86box_it-IT.qm</file>