Fixes named pipe bug with flags; updates readme usage

README.md

@@ -17,12 +17,12 @@ Once `tparse` is installed there are 2 ways to use it:
 Example:
 
 ```
-go test fmt -json | tparse
+go test fmt -json | tparse -all
 ```
 
 2. Save the output of `go test` with the `-json` flag into a file and call `tparse` with filename as an argument.
 
 ```
 go test fmt -json > fmt.out
-tparse fmt.out
+tparse -all fmt.out
 ```

main.go

@@ -137,7 +137,7 @@ func main() {
 // read from a named pipe (no args) or from single arg expected to be a faile path
 func getReader() (io.Reader, error) {
 
-	switch len(os.Args[1:]) {
+	switch flag.NArg() {
 	case 0: // Get FileInfo interface and fail everything except a named pipe (FIFO).
 
 		finfo, err := os.Stdin.Stat()
@@ -159,11 +159,6 @@ func getReader() (io.Reader, error) {
 
 	default: // Attempt to read from a file.
 
-		// After processing all flags, we should have one file to read from, fail otherwise.
-		if flag.NArg() < 1 {
-			flag.Usage()
-		}
-
 		dat, err := ioutil.ReadFile(os.Args[len(os.Args)-flag.NArg()]) // 🦄
 		if err != nil {
 			return nil, err