Dependencies

- Added dependencyGetBlocking and dependencyGetBlocked API calls, in
  the ongoing effort to find a workable API for dependencies.  The
  goal is to make the calling code as small as possible when dealing
  with dependencies.
- Corrected the algorithm for determining whether a task is blocked or
  blocking to also check that the other task is pending or waiting.
  For example:
    task add one
    task add two depends:1
    task do 1
  As the first task is completed, task 2 still depends on 1, but is
  no longer blocked due to the completed status.
- Modified the "info" report to use the modified API.

src/main.h

@@ -133,7 +133,9 @@ int handleExportYAML (std::string &);
 
 // dependency.cpp
 bool dependencyIsBlocked (Task&);
+void dependencyGetBlocked (Task&, std::vector <Task>&);
 bool dependencyIsBlocking (Task&);
+void dependencyGetBlocking (Task&, std::vector <Task>&);
 bool dependencyIsCircular (Task&);
 bool dependencyChainBroken (Task&);
 std::string dependencyNag (Task&);