Re-write argument parsing, implement skeleton of copy functionality

src/offline/copy.go

@@ -0,0 +1,21 @@
+package offline
+
+import (
+	"fmt"
+	"os"
+)
+
+func CopyField(targetLocation string, field rune) {
+	if isFile, _ := TargetIsFile(targetLocation, true); isFile {
+		//decryptedEntry := DecryptGPG(targetLocation)
+		// TODO implement clipboard support (maybe use third-party library?)
+		fmt.Println("In the future, this will copy " + string(field))
+	} else {
+		fmt.Println(AnsiError + "Failed to read \"" + targetLocation + "\" - it is a directory" + AnsiReset)
+	}
+	os.Exit(0)
+}
+
+func clipClear() {
+
+}