Demonstrators invaded the terminal building at Hong Kong International Airport for a second day Tuesday, forcing the cancellation of all flights out of the restive territory from the late afternoon. Scuffles broke out earlier in the day as black-clad protesters physically blocked and pushed back against travelers attempting to pass from the departure level through to security and immigration check points. “We’re supposed to be home right now,” said Sehem, a 23-year-old medical student trying to return to Europe.