Add self-contained gometalinter build tooling.

tools/vendor/github.com/kisielk/errcheck/README.md

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+# errcheck
+
+errcheck is a program for checking for unchecked errors in go programs.
+
+[![Build Status](https://travis-ci.org/kisielk/errcheck.png?branch=master)](https://travis-ci.org/kisielk/errcheck)
+
+## Install
+
+    go get -u github.com/kisielk/errcheck
+
+errcheck requires Go 1.6 or newer and depends on the package go/loader from the golang.org/x/tools repository.
+
+## Use
+
+For basic usage, just give the package path of interest as the first argument:
+
+    errcheck github.com/kisielk/errcheck/testdata
+
+To check all packages beneath the current directory:
+
+    errcheck ./...
+
+Or check all packages in your $GOPATH and $GOROOT:
+
+    errcheck all
+
+errcheck also recognizes the following command-line options:
+
+The `-tags` flag takes a space-separated list of build tags, just like `go
+build`. If you are using any custom build tags in your code base, you may need
+to specify the relevant tags here.
+
+The `-asserts` flag enables checking for ignored type assertion results. It
+takes no arguments.
+
+The `-blank` flag enables checking for assignments of errors to the
+blank identifier. It takes no arguments.
+
+
+## Excluding functions
+
+Use the `-exclude` flag to specify a path to a file containing a list of functions to
+be excluded.
+
+    errcheck -exclude errcheck_excludes.txt path/to/package
+
+The file should contain one function signature per line. The format for function signatures is
+`package.FunctionName` while for methods it's `(package.Receiver).MethodName` for value receivers
+and `(*package.Receiver).MethodName` for pointer receivers.
+
+An example of an exclude file is:
+
+    io/ioutil.ReadFile
+    (*net/http.Client).Do
+
+The exclude list is combined with an internal list for functions in the Go standard library that
+have an error return type but are documented to never return an error.
+
+
+### The deprecated method
+
+The `-ignore` flag takes a comma-separated list of pairs of the form package:regex.
+For each package, the regex describes which functions to ignore within that package.
+The package may be omitted to have the regex apply to all packages.
+
+For example, you may wish to ignore common operations like Read and Write:
+
+    errcheck -ignore '[rR]ead|[wW]rite' path/to/package
+
+or you may wish to ignore common functions like the `print` variants in `fmt`:
+
+    errcheck -ignore 'fmt:[FS]?[Pp]rint*' path/to/package
+
+The `-ignorepkg` flag takes a comma-separated list of package import paths
+to ignore:
+
+    errcheck -ignorepkg 'fmt,encoding/binary' path/to/package
+
+Note that this is equivalent to:
+
+    errcheck -ignore 'fmt:.*,encoding/binary:.*' path/to/package
+
+If a regex is provided for a package `pkg` via `-ignore`, and `pkg` also appears
+in the list of packages passed to `-ignorepkg`, the latter takes precedence;
+that is, all functions within `pkg` will be ignored.
+
+Note that by default the `fmt` package is ignored entirely, unless a regex is
+specified for it. To disable this, specify a regex that matches nothing:
+
+    errcheck -ignore 'fmt:a^' path/to/package
+
+The `-ignoretests` flag disables checking of `_test.go` files. It takes
+no arguments.
+
+## Cgo
+
+Currently errcheck is unable to check packages that `import "C"` due to limitations
+in the importer.
+
+However, you can use errcheck on packages that depend on those which use cgo. In
+order for this to work you need to `go install` the cgo dependencies before running
+errcheck on the dependant packages.
+
+See https://github.com/kisielk/errcheck/issues/16 for more details.
+
+## Exit Codes
+
+errcheck returns 1 if any problems were found in the checked files.
+It returns 2 if there were any other failures.
+
+# Editor Integration
+
+## Emacs
+
+[go-errcheck.el](https://github.com/dominikh/go-errcheck.el)
+integrates errcheck with Emacs by providing a `go-errcheck` command
+and customizable variables to automatically pass flags to errcheck.
+
+## Vim
+
+[vim-go](https://github.com/fatih/vim-go) can run errcheck via both its `:GoErrCheck`
+and `:GoMetaLinter` commands.