Enhancement - related to, but not fixing bug #293

- Added new attribute modifiers 'word' and 'noword' which find the existence
  of whole words, or prove the non-existence of whole words.  If a task has
  the description "Pay the bill", then "description.word:the" will match, but
  "description.word:th" will not.  For partial word matches, there is still
  "description.contains:th".
- Added unit tests for the text.cpp functions.
- Added unit tests including the new modifiers in filters.
- Added unit tests to parse the new modifiers.
- Modified man page.
- Modified the Context::autoFilter processing to use the new modifiers for
  +tag and -tag filtering.
- Added a support email to an error message, while looking at the filter code.
- Added new modifiers to the help report.
- Modified a utf8.t unit test to include an alphanumeric tag, rather than a
  smiley face.

src/tests/filt.t.cpp

@@ -34,7 +34,7 @@ Context context;
 ////////////////////////////////////////////////////////////////////////////////
 int main (int argc, char** argv)
 {
-  UnitTest test (14);
+  UnitTest test (20);
 
   // Create a filter consisting of two Att criteria.
   Filter f;
@@ -66,6 +66,7 @@ int main (int argc, char** argv)
   // Modifiers.
   Task mods;
   mods.set ("name", "value");
+  mods.set ("description", "hello, world.");
 
   Att a ("name", "is", "value");
   f.clear ();
@@ -124,6 +125,42 @@ int main (int argc, char** argv)
 "below"
 */
 
+  a = Att ("description", "word", "hello");
+  f.clear ();
+  f.push_back (a);
+  test.ok (f.pass (mods), "description:hello, world. -> description.word:hello = match");
+  // TODO test inverse.
+
+  a = Att ("description", "word", "world");
+  f.clear ();
+  f.push_back (a);
+  test.ok (f.pass (mods), "description:hello, world. -> description.word:world = match");
+  // TODO test inverse.
+
+  a = Att ("description", "word", "pig");
+  f.clear ();
+  f.push_back (a);
+  test.notok (f.pass (mods), "description:hello, world. -> description.word:pig = no match");
+  // TODO test inverse.
+
+  a = Att ("description", "noword", "hello");
+  f.clear ();
+  f.push_back (a);
+  test.notok (f.pass (mods), "description:hello, world. -> description.noword:hello = no match");
+  // TODO test inverse.
+
+  a = Att ("description", "noword", "world");
+  f.clear ();
+  f.push_back (a);
+  test.notok (f.pass (mods), "description:hello, world. -> description.noword:world = no match");
+  // TODO test inverse.
+
+  a = Att ("description", "noword", "pig");
+  f.clear ();
+  f.push_back (a);
+  test.ok (f.pass (mods), "description:hello, world. -> description.noword:pig = match");
+  // TODO test inverse.
+
   return 0;
 }