Add vendor folder to git

vendor/github.com/ugorji/go/codec/codecgen/README.md

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+# codecgen tool
+
+Generate is given a list of *.go files to parse, and an output file (fout),
+codecgen will create an output file __file.go__ which
+contains `codec.Selfer` implementations for the named types found
+in the files parsed.
+
+Using codecgen is very straightforward.
+
+**Download and install the tool**
+
+`go get -u github.com/ugorji/go/codec/codecgen`
+
+**Run the tool on your files**
+
+The command line format is:
+
+`codecgen [options] (-o outfile) (infile ...)`
+
+```sh
+% codecgen -?
+Usage of codecgen:
+  -c="github.com/ugorji/go/codec": codec path
+  -o="": out file
+  -r=".*": regex for type name to match
+  -nr="": regex for type name to exclude
+  -rt="": tags for go run
+  -t="": build tag to put in file
+  -u=false: Use unsafe, e.g. to avoid unnecessary allocation on []byte->string
+  -x=false: keep temp file
+
+% codecgen -o values_codecgen.go values.go values2.go moretypedefs.go
+```
+
+Please see the [blog article](http://ugorji.net/blog/go-codecgen)
+for more information on how to use the tool.
+