Fix bug #5371117 Regression : The Hebrew / Arabic text behavior in ICS latest build is wrong

- welcome back start / count
- goodbye log clusters
- clean Paint code
- make private some functions as they should be
- improve memory allocation (create only one Shaper and reuse it for for shaping the runs in
the same input text)

Change-Id: I89a320c7f041319851308c8c9a919fbeafa82cdd