Merge pull request #151 from zeux/nuget

.gitignore

appveyor.yml

scripts/nuget.autopkg

scripts/nuget/build/native/pugixml-propertiesui.xml

scripts/nuget/build/native/pugixml.targets

scripts/nuget/pugixml.nuspec

scripts/nuget_build.ps1

scripts/pugixml_vs2010.vcxproj

scripts/pugixml_vs2010_static.vcxproj

scripts/pugixml_vs2013.vcxproj

scripts/pugixml_vs2013_static.vcxproj

scripts/pugixml_vs2015_static.vcxproj

scripts/pugixml_vs2017_static.vcxproj