Add bunch of missing symbols to the manual, and go over several
  docstrings reformatting them for the benefit of the documentation
  generator.

  (A crapton of symbols are still not in the manual.)

 Call RANDOM just once, and build an inline binary search tree
 for O(log n) goodness instead of O(n).

 Patch by: Gustavo <gugamilare@gmail.com>

 * More efficient with constant arguments.

 * Respect lexical environment with non-constant arguments.

Patch by Stelian Ionescu.

 * Thanks to Andreas Fuchs -- I only took the liberty of changing the name from
   MULTIPLE-VALUE-OR to NTH-VALUE-OR.

 - support #'eq and 'eq style :test arg
 - support T and OTHERWISE clause instead of the :default keyword arg

Added:
 * XOR
 * WHICHEVER
 * SWITCH, ESWITCH, CSWItCH
 * UNIONF, NUNIONF
 * ALIST-PLIST, PLIST-ALIST
 * ENSURE-CONS
 * NAMED-LAMDBA
 * DEFINE-CONSTANT
 * STRING-DESIGNATOR

Note:
 Documentation strings of many new operators are sorely lacking, particularly
 NAMED-LAMBDA and *SWITCH.