delete testDavidMain File
Merge remote-tracking branch 'origin/DavidWin' into Sherry
not important
update functions about Line class
update Line functions
dave thing
solve conflicts in header file
Merge remote-tracking branch 'origin/DavidWin' into Sherry
Merge remote-tracking branch 'origin/DavidWin' into Sherry
correct
add translate functions and explanations
merged all tranformation

Complete untested transformation class