Add new option "-s" to run_xgettext. Fix paths.
Add new option "-s" to run_xgettext. Fix paths.

with this option, current directory is scanned for strings, and message.po is saved in lang/C subdir.
This is usefull when developing new addons outside from friendica tree.

tobiasd/friendica,annando/friendica,fabrixxm/friendica,dissolve/friendica,annando/friendica,tugelbend/friendica,dissolve/friendica,fabrixxm/friendica,fabrixxm/friendica,friendica/friendica,tugelbend/friendica,annando/friendica,tugelbend/friendica,tobiasd/friendica,dissolve/friendica,friendica/friendica,friendica/friendica,tobiasd/friendica,fabrixxm/friendica,dissolve/friendica,annando/friendica,friendica/friendica,tobiasd/friendica,dissolve/friendica,tobiasd/friendica,tugelbend/friendica,fabrixxm/friendica,tugelbend/friendica,friendica/friendica,annando/friendica