Regexes

- Added regex support to substirutions.
- Fixed bug that prevented 1.9.4 from shipping with regexes.  If the
  description is "aXXaaXXa", and the substitution is /XX/.../ then the
  first substitutions changes the length of the string to "a...aaXXa"
  and therefore invalidates the index for the second match, and makes
  this change: "a...a...Xa".  The fix is to keep a running 'skew' count
  of the difference in 'from' and 'to' length, to adjust the match
  indexes.
- Moved the helper deltaSubstitutions function into the Task object,
  which makes more sense.
- Cleaned up output composition for CmdAdd.
- Eliminated #ifdef FEATURE_REGEX.  They are here to stay.

src/Arguments.cpp

@@ -786,9 +786,9 @@ bool Arguments::is_subst (const std::string& input)
   std::string from;
   std::string to;
   Nibbler n (input);
-  if (n.skip     ('/')            &&
-      n.getUntil ('/', from)   &&
-      n.skip     ('/')            &&
+  if (n.skip     ('/')       &&
+      n.getUntil ('/', from) &&
+      n.skip     ('/')       &&
       n.getUntil ('/', to)   &&
       n.skip     ('/'))
   {