Replace participle with PEG based parser

grammar/ast.go

@@ -0,0 +1,33 @@
+package grammar
+
+type Node interface{}
+
+type Telegram struct {
+	Header *Header
+	Data   []*Object
+	Footer *Footer
+}
+
+type Header struct {
+	Value string
+}
+
+type Footer struct {
+	Value string
+}
+
+// Object is a COSEM object in the Telegram represented by the
+// OBIS (Object Identification System) and one or more attributes.
+type Object struct {
+	Id    *OBIS
+	Value interface{}
+}
+
+// ...
+type OBIS struct {
+	A int
+	B int
+	C int
+	D int
+	E int
+}