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.
Use [], not at() when the index is guaranteed to be valid.
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").
htmlreport: on the index page, print stats of which warning ID occured how often.
Merge pull request #372 from Dmitry-Me/dontUseArrayAtWhenItWouldntThrow

Use [], not at() when the index is guaranteed to be valid.
Cache option flags and check them first.
Merge pull request #373 from Dmitry-Me/cacheOptionFlagsAndCheckThemFirst

Cache option flags and check them first.
Use temp variables to avoid repeated actions in code.
Merge pull request #374 from Dmitry-Me/useTempVariablesToAvoidRepeatedActions

Use temp variables to avoid repeated actions in code.
Resolve CID 1214637.
Merge pull request #376 from Dmitry-Me/resolveIssue1214637

Resolve CID 1214637.
Bring declarations closer to where they're needed.
htmlreport: stats: sort primary by occurrences but if several IDs occur equally often, sort them alphabetically.
Merge pull request #377 from Dmitry-Me/bringDeclarationsCloserToWhereTheyreNeeded

Bring declarations closer to where they're needed.
Fix Cppcheck warning. Make function Preprocessor::readpreprocessor static instead of const.
Reuse previously computed values, use more const.
Merge pull request #378 from Dmitry-Me/reusePreviouslyComputedValues

Reuse previously computed values, use more const.