Scalable Comments, auto-positioning scaled scripts

including support for auto-positioning scaled scripts (so you don't
have to clean-up when scaling blocks)
motd support

On startup Snap! looks for http://snap.berkeley.edu/motd.txt, if it
exists it is shown in a dialog box
GUI: fix for #run: URL switch
update Portuguese localization

All i18n strings included in the German l10n are now translated to
Portuguese. The comments in the file have also been partially
translated (where it made sense). The lang-pt.js and lang-de.js now
have parallel structures, since this makes it much easier to check for
missing translations.