Added message of the day and made it properly configurable using /#setting (not saved to config file yet)

Made picking items up in creative mode delete them (because they usually are in the inventory already anyway)

Lowered default viewing range minimum to such that it allows fairly good framerate in jungles with sucky hardware.
Almost all computers stick to the minimum with the current farmesh range that someone has set up without asking from me, but farmesh is not used as default anyway so those that use it can raise the lower limit in their configuration as they wish.

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.

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