Change/Fix: Require peg 1.0, fix variable binding depth errors

Had to (and needed to, anyway) use peg-1.0.  And while this does less
macro magic, and less magic with cl-eval-when, I couldn't get around
using eval.  I wish peg had a function that takes a list of rules and
returns a predicate that matches a string or at point.  (I tried to
work around the lack of that by using parts of peg macros, but it's
very complicated, and everything I tried had one problem or another.)

README.org

@@ -524,6 +524,7 @@ Simple links may also be written manually in either sexp or non-sexp form, like:
 
 *Internal*
 +  Predicates are now defined more cleanly with a macro (=org-ql-defpred=) that consolidates functionality related to each predicate.  This will also allow users to more easily define custom predicates.
++  Version 1.0 of library ~peg~ is now required.
 
 ** 0.5