Put the gettext init code in a macro and define it appropriately
depending on whether gettext is actually available or not.

This partially reverts 023cc0d37776976b4b192b7363f73a5d2debdef6, goes
back to using PROJECT_NAME for the filename and also uses PROJECT_NAME
as text domain in the source code.

fixed error if gettext is disabled

Fixed the problem of <=r548 clients fucking up maps on >=r549 servers. Also, already fucked up maps are now loaded correctly.

Get rid of the system-specific updatelocales.sh and introduce an
updatepo cmake rule. po files are also updated before creating the mo
files, and we now keep the .pot file (in the po/en directory). To
stabilize the po file creation, file contents are sorted by source
filename.

Update po files in the process.

Get rid of the system-specific updatelocales.sh and introduce an
updatepo cmake rule. po files are also updated before creating the mo
files, and we now keep the .pot file (in the po/en directory). To
stabilize the po file creation, file contents are sorted by source
filename.

Update po files in the process.

The po file should not be named c55 if we're in ∆. But since it is not
exposed at installation time, we don't actually need its name to be
based on the project name at all, so just call it minetest.po

The po file should not be named c55 if we're in ∆. But since it is not
exposed at installation time, we don't actually need its name to be
based on the project name at all, so just call it minetest.po