[Inkscape-translator] Updated Japanese translations

Hi,

Naoki and I updated the Japanese translations in accordance with 0.45pre2 and uploaded on the patch tracker.

Here is the newly created translation for Windows installer (japanese.nsh): https://sourceforge.net/tracker/index.php?func=detail&aid=1646292&gr...

Here is an update, succeeded from the former translators, of po file (ja.po): https://sourceforge.net/tracker/index.php?func=detail&aid=1647723&gr...

Best regards,