tools: various improvements in nfdc

* use same underlying type for ParseMode and AvailableIn,
  to avoid potential errors when converting between them
* simplify AvailableIn stream output operator with text::Separator
* allow CommandParser::addCommand to accept bitwise OR'ed modes
* qualify nfdc logging sources with 'nfdc.' prefix

refs #3780

Change-Id: I2eee3d562184daf27305c2d5f2892637b63421c2
diff --git a/tools/nfdc/format-helpers.hpp b/tools/nfdc/format-helpers.hpp
index 84efe7b..6629409 100644
--- a/tools/nfdc/format-helpers.hpp
+++ b/tools/nfdc/format-helpers.hpp
@@ -85,6 +85,12 @@
   explicit
   Separator(const std::string& subsequent);
 
+  int
+  getCount() const
+  {
+    return m_count;
+  }
+
 private:
   std::string m_first;
   std::string m_subsequent;