bugfixes and beatuification of trivium
1. velocity replaced by speed in field - more accurate
2. velocity replay enabled - was not there
3. Help pushed to right top
4. Back now logged as a normal button
5. TutoringEnddialog cleaned up (again)
6. Slider control - distinguish system and user events and log
separately
7. ExplanationBox - ability to show Revise alone - not yet enabled
8. ParameterProber - was not showing explanation on mistake.