ui: file not up to date display

* the codeview now displays a hatched background for a filename when the file's content has changed or the file does not exist anymore.
* added TimePoint class to encapsulate boost.

src/lib/utility/TimePoint.cpp

@@ -0,0 +1,21 @@
+#include "TimePoint.h"
+
+TimePoint::TimePoint()
+	: m_time(boost::posix_time::not_a_date_time)
+{
+}
+
+TimePoint::TimePoint(boost::posix_time::ptime t)
+	: m_time(t)
+{
+}
+
+//TimePoint::TimePoint(time_t t)
+//{
+// needs an implementation
+//}
+
+TimePoint::TimePoint(std::string s)
+{
+	m_time = boost::posix_time::time_from_string(s);
+}