add [feature] arg. Use for  GlobalLexicalModel. Not tested
add [feature] arg. Use for GlobalLexicalModelUnlimited. Not tested
move code from LoadSourceWordDeletionFeature to constructor in class SourceWordDeletionFeature. Don't understand how it loads weights
move code from LoadTargetWordInsertionFeature to constructor in class TargetWordInsertionFeature. Don't understand how it loads weights
move code from LoadPhraseBoundaryFeature() to constructor in class PhraseBoundaryFeature
move code from LoadPhraseLengthFeature() to constructor in class PhraseLengthFeature