`Patacode update

[Gregg Reynolds <gar at arabink dot com>]

Changes:

Some stuff about regexes;  minor changes to Preface; some notes in 
Theory chapter; some notes on digit polarity in Unicode mapping; 
arabic-1 changes: alif maqsura to à and Ä; dotless b from ß to "P"; 
dotless f to ß; dotless qaf to q; remove half-extender; change tiny siin 
to ¾, tiny nuun to ¼; add veh after peh; add rad shadda, rename 
"semantic shadda" to "lexical shadda";  added colophon

-gregg