fix TokenTypes compatibility problems between 6.15 and 6.16

[romani]

Commit 23e6eba

damaged compatibility between 6.16 and all previous releases.
checkstyle-6.15-all.jar:/com/puppycrawl/tools/checkstyle/grammars/GeneratedJavaTokenTypes.txt
checkstyle-6.16-all.jar:/com/puppycrawl/tools/checkstyle/grammars/GeneratedJavaTokenTypes.txt

[romani]

We need to find way to prevent this to happen in Future by CI.

[sabaka]

And we should add additional comments to grammar with warning, I think. We have something like "put new tokens only in the end", but nothing about deletion.

[romani]

Nobody read comments.... UTs should teach future contributor and control us.