message: docs: Add preliminary 1.9 changelog
  Still trying to decide if the next version should be 1.9 or 1.8x and
  what other changes need to go in.
diff: @@ -2120,6 +2120,31 @@ Because of the differences in document object models, performance considerations
  :!numbered:
  +[[v1.9]]
  +=== v1.9 ^2018-??-??^
  +
  +* Specification changes:
  + . `xml_document::load(const char*)` (deprecated in 1.5) now has `deprecated` attribute; use `xml_document::load_string` instead
  + ` `xml_node::select_single_node` (deprecated in 1.5) now has `deprecated` attribute; use `xml_node::select_node` instead
  +
  +* New features:
  + . Add move semantics support for xml_document and improve move semantics support for other objects
  + . CMake build now exports include directories
  + . CMake build with BUILD_SHARED_LIBS=ON now uses dllexport attribute for MSVC
  +
  +* XPath improvements:
  + . Rework parser/evaluator to not rely on exceptional control flow; longjmp is no longer used when exceptions are disabled
  + . Improve error messages for certain invalid expressions such as `.[1]` or `(1`
  + . Minor performance improvements
  +
  +* Compatibility improvements:
  + . Fix Texas Instruments compiler warnings
  + . Fix compilation issues with limits.h for some versions of gcc
  + . Fix compilation issues with Clang/C2
  + . Fix implicit fallthrough warnings in gcc 7
  + . Fix cray++ compiler errors
  + . Fix unsigned integer overflow errors with -fsanitize=integer
  +
  [[v1.8]]
  === v1.8 ^2016-11-24^
  