Add new option to identify new vs existing code

[yogeshsGIT]

By default entire file gets scanned for rules, Can we get an option to identify new code vs existing code and rules will be applied only on new code, this will help in identifying the issues reported by CFLint on new code only and issues on existing code will be ignored. We have an option of Base version in SonarServer, can we get similar option for CFLint where it can be integrated with GIT repo which will be considered as base code to check against with. We do have an option for Line level or rule level ignore but that's change in exiting code which we want to avoid