Add simple xml debug output. When both --xml and --debug is used there will be xml debug output.
Get rid of tokAt() and strAt() in trivial cases.
Merge pull request #363 from Dmitry-Me/dontRunTheAtLoopWhenNotNeeded

Get rid of tokAt() and strAt() in trivial cases.
astyle formatting

[ci skip]
Fixed #5982 (Add xml dump)
xml dump: remove duplicate attribute
xml dump: output a <variables> with all variables
xml dump: Fixed segfault when dumping symboldatabase variables
xml dump: fixed some minor issues in symboldatabase dump
xml dump: fixed some bad xml output in the token list dump
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.