Make error handling work on older versions of libxml_ruby.  Fixes
Update version to 2.6.0
Merge branch 'master' of github.com:xml4r/libxml-ruby
More history updates.
Upgrade to VC 2012.
Fix for github issue #59, segmentation fault after failure to load external schema
Merge pull request #60 from cjheath/master

Fix for Github issue #59, segmentation fault after failing to load external schema
Fix potential segfault when GC occurs while creating ns from xpath

rxml_xpath_object_wrap() was creating a Ruby array and it looks like
Ruby's garbage collection was unable to find it on the stack.
Merge pull request #61 from ender672/xpath_namespace_gc

Fix potential segfault when GC occurs while creating ns from xpath