fix infinite loop bug when reading test cases
fix infinite loop bug when reading test cases

- pushing character back onto stream causes stream state to never fail
  when test cases contain string and/or vector<string> for
  paramater/return values
- simplest case found so far: parameter: string, return: string

chazmcgarvey/vimcoder,chazmcgarvey/vimcoder,chazmcgarvey/vimcoder