CLI2: Simplify context determination

Simlifies by offloading portion of the logic into the singleton Context
class (which has nothing to do with the task context per se, just a
implementation singleton).

src/Context.cpp

@@ -922,6 +922,35 @@ int Context::getHeight ()
   return height;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+std::string Context::getTaskContext (const std::string& kind, bool fallback /* = true */)
+{
+  // Detect if any context is set, and bail out if not
+  std::string contextName = config.get ("context");
+  if (! contextName.empty ())
+    debug (format ("Applying context '{1}'", contextName));
+  else
+  {
+    debug ("No context set");
+    return "";
+  }
+
+  // Figure out the context string for this kind (read/write)
+  std::string contextString = config.get ("context." + contextName + "." + kind);
+  if (contextString.empty ())
+  {
+    debug ("Specific " + kind + " context for '" + contextName + "' not defined. ");
+    if (fallback)
+    {
+      debug ("Falling back on generic.");
+      contextString = config.get ("context." + contextName);
+    }
+  }
+
+  debug (format ("Detected context string: {1}", contextString.empty() ? "(empty)" : contextString));
+  return contextString;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 bool Context::color ()
 {