Enable an old version of segmentation plugin

A directory 'plugins' can be created at the root of the binary
directory to load automatically plugins fro it

Fallback to system default

By default, start with the system default language

so it is cleaner to set the right name for this operation, and use proper
internationalization process to get the right translations

The variable is used in Detiq-T to copy translations files (*.qm)
to the 'lang' subfolder