[Error] (refactoring) Improve comments.

- Improve comments in ExceptionHolder.h, especially of StdExceptionHolder.
[Test] (minor) Improve PathSuite.

- Confirm that boost::path would automatically merges the '/' when combining.
[version] 1.20.0
[Test] (minor) Improve DateTimeSuite.

- Confirm boost::date_time can parse a ISO datetime without seconds part.
[Test] [Android] Add more suites.

- Add Data, DateTime and Lexical packages suites.
[Test] (minor) Move all test data into assets directory.

- Add AssetPath utils which provide a path to the assets directory on each system. The first implementation is Win32.
Merge branch 'master' into ndk_r10c
[Test] [Android] Get AssetManager.

- We get AssetManager in Java and passed it to AndroidRun.cpp . Not used yet.