Merge branch 'release/0.9.21'

Godeps/Godeps.json

Godeps/_workspace/src/github.com/ethereum/ethash/ethash.go

...orkspace/src/github.com/ethereum/ethash/src/python/core.c

Godeps/_workspace/src/github.com/huin/goupnp/goupnp.go

Godeps/_workspace/src/golang.org/x/net/html/atom/atom.go

...ps/_workspace/src/golang.org/x/net/html/atom/atom_test.go

Godeps/_workspace/src/golang.org/x/net/html/atom/gen.go

Godeps/_workspace/src/golang.org/x/net/html/atom/table.go

...s/_workspace/src/golang.org/x/net/html/atom/table_test.go

...s/_workspace/src/golang.org/x/net/html/charset/charset.go

...rkspace/src/golang.org/x/net/html/charset/charset_test.go

Godeps/_workspace/src/golang.org/x/net/html/charset/gen.go

Godeps/_workspace/src/golang.org/x/net/html/charset/table.go

.../golang.org/x/net/html/charset/testdata/HTTP-charset.html

...ng.org/x/net/html/charset/testdata/HTTP-vs-UTF-8-BOM.html

...org/x/net/html/charset/testdata/HTTP-vs-meta-charset.html

...org/x/net/html/charset/testdata/HTTP-vs-meta-content.html

.../x/net/html/charset/testdata/No-encoding-declaration.html

...rkspace/src/golang.org/x/net/html/charset/testdata/README

.../golang.org/x/net/html/charset/testdata/UTF-16BE-BOM.html