Implement Cobra CLI tooling, Viper config tooling (#336)

* start pulling out + replacing urfave and config

* replace many many instances of config

* move more stuff => viper

* properly remove urfave

* move some flags to root command

* add testrig commands to root

* alias config file keys

* start adding cli parsing tests

* reorder viper init

* remove config path alias

* fmt

* change config file keys to non-nested

* we're more or less in business now

* tidy up the common func

* go fmt

* get tests passing again

* add note about the cliparsing tests

* reorganize

* update docs with changes

* structure cmd dir better

* rename + move some files around

* fix dangling comma

vendor/gopkg.in/ini.v1/data_source.go

@@ -0,0 +1,76 @@
+// Copyright 2019 Unknwon
+//
+// Licensed under the Apache License, Version 2.0 (the "License"): you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package ini
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+)
+
+var (
+	_ dataSource = (*sourceFile)(nil)
+	_ dataSource = (*sourceData)(nil)
+	_ dataSource = (*sourceReadCloser)(nil)
+)
+
+// dataSource is an interface that returns object which can be read and closed.
+type dataSource interface {
+	ReadCloser() (io.ReadCloser, error)
+}
+
+// sourceFile represents an object that contains content on the local file system.
+type sourceFile struct {
+	name string
+}
+
+func (s sourceFile) ReadCloser() (_ io.ReadCloser, err error) {
+	return os.Open(s.name)
+}
+
+// sourceData represents an object that contains content in memory.
+type sourceData struct {
+	data []byte
+}
+
+func (s *sourceData) ReadCloser() (io.ReadCloser, error) {
+	return ioutil.NopCloser(bytes.NewReader(s.data)), nil
+}
+
+// sourceReadCloser represents an input stream with Close method.
+type sourceReadCloser struct {
+	reader io.ReadCloser
+}
+
+func (s *sourceReadCloser) ReadCloser() (io.ReadCloser, error) {
+	return s.reader, nil
+}
+
+func parseDataSource(source interface{}) (dataSource, error) {
+	switch s := source.(type) {
+	case string:
+		return sourceFile{s}, nil
+	case []byte:
+		return &sourceData{s}, nil
+	case io.ReadCloser:
+		return &sourceReadCloser{s}, nil
+	case io.Reader:
+		return &sourceReadCloser{ioutil.NopCloser(s)}, nil
+	default:
+		return nil, fmt.Errorf("error parsing data source: unknown type %q", s)
+	}
+}