+htp #15931 Import RespondWithDirectives from spray
+htp #15918 import CacheConditions from spray
+htp #15919 import CookieDirectives
!htp rename conflicting withExecutionContext directive to extractExecutionContext
+htp add RequestContext/BasicDirectives.withLog/extractLog
Merge pull request #16108 from spray/w/port-more-directives

Fixes for 15931, 15918, 15919