wings_convert needs path update

[simbad]

Hello,
as I want to use some wings models in a graphics pipeline (only a very small one for home use) I looked out for some conversion tools.

I do find the wings_convert that did not find the import_export plugins. So I had a look into the script and found a wrong path to the plugins.

should be

"plugins/default/import_export"

As I am not very active in the development maybe someone will find the time to fix this as it is easy todo and has a big benefit for everyone who wants to convert the wings files from within scripts.

Thanks.