Merge branch 'release-0.1.1'
Fixes compilation errors: adds missing include, namespace.
Merge branch 'hotfix-0.1.2'
Moves html_attribute to separate file.
Adds html_writer related class declarations to separate header.
Temporarily disables xpath support.
Adds html_node related declarations to appropriate header.
Removes html_writer and html_node related class declarations from pugihtml.hpp.
Adds missing includes.
Moves html_writer implementation so separate file.
Adds separate utf_decoder header.
Adds missing include.
Adds more functions to pugiutil.
Adds more classes to html_writer.
Adds html_node class declarations to appropriate files.
Removes code from pugihtml.cpp that was moved to separate modules.