Enhancement - Sequence range limiting

- Prevents overly large ranges.  A bug was reported from a user
  who tried this:

    % task annotate 1 1-987654321

  The 1-987654321 was assumed to be a valid range, and caused task
  to consume all available memory.  The workaround was:

    % task 1 annotate 1-987654321

  But it seems a good idea to range-limit sequences.  Currently
  it is 1000.  Perhaps this should be configurable.

src/Sequence.cpp

@@ -83,8 +83,8 @@ void Sequence::parse (const std::string& input)
         if (low > high)
           throw std::string ("Inverted sequence range high-low");
 
-        if (high - low > 1000)
-          throw std::string ("Range too large, exceeded 1,000 IDs");
+        if (high - low >= SEQUENCE_MAX)
+          throw std::string ("ID Range too large");
 
         for (int i = low; i <= high; ++i)
           this->push_back (i);

src/Sequence.h

@@ -30,6 +30,8 @@
 #include <vector>
 #include <string>
 
+#define SEQUENCE_MAX 1000
+
 class Sequence : public std::vector <int>
 {
 public:

src/tests/seq.t.cpp

@@ -90,7 +90,7 @@ int main (int argc, char** argv)
   seq = parseSequence ("1--2");
   t.is (seq.size (), (size_t)0, "seq '1--2' -> 0 items (error)");
 
-  // 1-1000
+  // 1-1000 (SEQUENCE_MAX);
   seq = parseSequence ("1-1000");
   t.is (seq.size (), (size_t)1000, "seq '1-1000' -> 1000 items");
   if (seq.size () == 1000)