* unify error handling
* V2: attribute version must be 2; tag errors must exist
No meaningful forceIncludes error message
fix for #225:
* old: 15:55:16.367 WARN  - [:1]: cannot find the sources for '#include'
* new: 15:55:16.367 WARN  - [sonar.cxx.forceIncludes:1]: cannot find the sources for 'VS10Macros.h'