Merge new changes to unordered & hash.

- Unordered tests can run lightweight test or Boost.Test (at least
   theoretically).
 - Workaround Open BSD's incorrect numeric_limits.
 - Move the hash extensions in their own file.
 - Various small improvements to the unordered docs.
 - Fix some unordered examples.

Merged revisions 43117-43837 via svnmerge from 
https://svn.boost.org/svn/boost/branches/unordered/trunk


[SVN r43838]

hash/doc/Jamfile.v2

@@ -12,4 +12,15 @@ boostbook standalone : hash :
     <xsl:param>chunk.section.depth=2
     <xsl:param>generate.section.toc.level=2
     <xsl:param>toc.section.depth=1
-    <xsl:param>toc.max.depth=1 ;
+    <xsl:param>toc.max.depth=1
+
+    <dependency>css
+    <dependency>images
+    ;
+
+install css : [ glob $(BOOST_ROOT)/doc/src/*.css ]
+    : <location>html ;
+install images : [ glob $(BOOST_ROOT)/doc/src/images/*.png ]
+    : <location>html/images ;
+explicit css ;
+explicit images ;