[JENKINS-17450] "warning" and "performance" not counted

- The graph doesn't consider "No Category" and whole plugin doesn't work with "portability" severity at all.
- "No category" and "portability" severities added at all places in the code where other severities are used. Configuration files now contain these additional values.
- Align of the displayed severities updated on the configuration page to use 2 rows and 4 columns.
- CppcheckParser is now able to parse the portability severity correctly, it used incorrect "no category". This is only for report version 2, version 1 doesn't output it.
- REST API extended to contain portability severity too.
- Legend "Severity 'SEVERITY'" in the graph updated to equivalent but much shorter "SEVERITY". There is more space for the data in the trend now.
- Non-parametric constructor added to CppcheckStatistics class to simplify creation of empty instance.
- Support for localization implemented at many places instead of hardcoded strings.
- Incorrect @SuppressWarnings anotations removed to fix compiler warnings.