Updated the ISummaryGenerator interface.

- renamed FileInfo struct to MatchingFile to avoid conflict with the
  built-in FileInfo
- replaced file path with a FileInfo structure in MatchingFile struct
- modified ISearchSummary.Generate parameter list: added searchQuery
  and inputPaths
Fixed ISummaryGenerator interface and its implementation

- fixed access modifier on MatchingFile.fileInfo
- fixed SummaryGenerator so that it correctly implements ISummaryGenerator