Output of -PV was not suitable for inputting to -m-, key was missing. (#1970)

* Output of -PV was not suitable for inputting to -m-, key was missing.

Fix #1969

* Make V flag to -P also print the type

This makes -PV work also for non-built-in tags (of which their type is
not known by exiv2).

* Adjust man to accomodate for the V flag change

tests/bugfixes/github/test_issue_1969.py

@@ -0,0 +1,16 @@
+# -*- coding: utf-8 -*-
+
+import system_tests
+
+
+class TestPrintPlainWithSet(metaclass=system_tests.CaseMeta):
+
+    url = "https://github.com/Exiv2/exiv2/issues/1969"
+
+    filename = "$data_path/smiley1.jpg"
+    commands = ["$exiv2 -K Exif.Image.ImageDescription -PV $filename"]
+    stdout = [
+        """set Exif.Image.ImageDescription                  Ascii      Well it is a smiley that happens to be green
+"""
+    ]
+    retval = [0]