lang: Replace the go-bindata usage with embed

This doesn't let us have nested mcl at the moment, but we could improve
on this with an embed API for each package. For now this makes building
the project easier.

test/test-gometalinter.sh

@@ -47,7 +47,6 @@ gml="$gml --enable=misspell"
 # TODO: at least until https://github.com/alecthomas/gometalinter/issues/270
 gml="$gml --exclude=lang/parser/lexer.nn.go"
 gml="$gml --exclude=lang/parser/y.go"
-gml="$gml --exclude=bindata/bindata.go"
 gml="$gml --exclude=lang/types/kind_stringer.go"
 gml="$gml --exclude=lang/interpolate/parse.generated.go"