A few translated string added in Anjuta 2.91.6

[Sébastien Granjoux <seb sfo free fr>]

Hi,


The makefile backend plugin (plugins/mk-project) has been ported to the 
new project manager API and re-enable in anjuta. It contains a few 
translated strings:

"Group"
"Source"
"Unknown"
"Unable to parse make file"
"Project doesn't exist or invalid path"
"Project doesn't allow to set properties"

Most of these strings have already been translated for the autotools 
backend plugin (plugins/am-project)


Regards,

Sébastien