Task Data Parsing

- Improved the handling when parsing blank lines and empty task in the data, so
  that instead of the message:

    Taskwarrior no longer supports file format 1, originally used between 27
    November 2006 and 31 December 2007.

  We now see:

    Unrecognized Taskwarrior file format or blank line in data.

- Merged t2.t.cpp into t.t.cpp.

test/CMakeLists.txt

@@ -10,7 +10,7 @@ include_directories (${CMAKE_SOURCE_DIR}
                      ${TASK_INCLUDE_DIRS})
 
 set (test_SRCS autocomplete.t col.t color.t config.t fs.t i18n.t json.t list.t
-               msg.t nibbler.t rx.t t.t t2.t t3.t tdb2.t text.t utf8.t util.t
+               msg.t nibbler.t rx.t t.t t3.t tdb2.t text.t utf8.t util.t
                view.t json_test lexer.t iso8601d.t iso8601p.t eval.t dates.t
                variant_add.t variant_and.t variant_cast.t variant_divide.t
                variant_equal.t variant_exp.t variant_gt.t variant_gte.t