allow one more char in quid; make a responsory quid unbreakable
typographus task - switch to use xelatex
new macro psalmGroup; wrep psalmodic units (psalms/psalm groups) in new environment psalmodia

- the latter change is backwards incompatible, older booklets don't define this environment;
it's purpose is to be able to set a psalm group in one two-column layout, not as single
psalms one under another
psalm groups set in a more convenient way

(in the Midday hour and in the Vigil)