fixed column indexing

position.go

@@ -10,7 +10,7 @@ func (p *Position) Advance(rn rune) {
 	p.Index++
 	if rn == '\n' {
 		p.Line++
-		p.Column = 0
+		p.Column = 1
 	} else {
 		p.Column++
 	}

reader.go

@@ -18,7 +18,7 @@ func New(r io.Reader) *Reader {
 	return &Reader{
 		buf: ds.NewArrayStack[posRune](),
 		src: bufio.NewReader(r),
-		pos: &Position{Index: 0, Line: 1, Column: 0},
+		pos: &Position{Index: 0, Line: 1, Column: 1},
 	}
 }