travis: remove unneeded suppressions from self-check.
Merge pull request #371 from matthiaskrgr/travis_working

travis: remove unneeded suppressions from self-check.
Fixed #5996 (false positive: Clarify calculation precedence for '+' and '?'.)
xml dump: Added function attribute in scope
Fixed #5978 (false positive: Array 'm_pool_vector[-1]' accessed at index 0, which is out of bounds.)
xml dump: added 'astIsFloat' utility function in cppcheckdata.py
htmlreport: fix #5998, crash on some files with "UnicodeDecodeError".
For those files that we can't decode, don't generate a html-preview but note into index.html that we couldn't process the file.
At the end, summarize on which files we failed and suggest using --source-encoding option.
xml dump: add more token attributes
htmlreport: sort error-data per line (in index.html page as well as in the defect list of the respective files.)
htmlreport: if no arguments are passed, print --help output; when done generating the report, print where index.html is (take report_dir into account).
htmlreport: don't crash when pygments fails to determine filetype of a file we want to highlight. This happens for files with no extension (for example "foo" instead of "foo.c").
travis: replace kernel check with clang check.

Check clang instead of kernel, which is a lot faster.
Make clang check failure fatal to the build.
travis: add -DCHECK_INTERNAL to the VERIFY=1 job to automatically fetch issues like #5869 via travis, check clang with --exception-handling
travis: make clang check sensitive to internal cppcheck errors.