Don't fail hard if broken analysis is used.

Today an analysis chain with broken tokenfilters or tokenizers like
WordDelimiterFilter might produce somewhat broken term vectors that cause
`StringIndexOutOfBoundsExceptions` if FastVectorHighlighter is used
since the positions / offsets contract is violated and offsets of highlight
tokens are not increasing but decreasing even if their positions are increasing.

Yet, if we detect such a situation we can resort the tokens which might cause
somewhat odd highlights but doesn't fail hard with a StringIndexOOBException.

Closes #3006