Merge lexical_cast and some conversion docs and  test from trunk:
* fixed int128 and uint128 conversions (fixes #8790)
* fixed warnings from Boost Inspection Report

[SVN r85160]
Merge from trunk:
* Do not treat critcal errors as bad_lexical_cast exceptions, but if exceptions are on, throw correct exception instead (refs #8966)

[SVN r85331]
Merge lexical_casts documentation and tests to release branch (refs #9046)

[SVN r85901]