[master] Refactor structure

Author: Robert Akhmerov

main.go

@@ -3,5 +3,5 @@ package main
 import "github.com/zored/edit/src/cmd"
 
 func main() {
-  cmd.Execute()
+	cmd.Execute()
 }

src/service/navigation/position.go

@@ -0,0 +1,14 @@
+package navigation
+
+import (
+	"fmt"
+)
+
+type Position struct{ Column, Line int }
+
+func NewPosition(line int, column int) *Position { return &Position{Column: column, Line: line} }
+
+func (p Position) String() string    { return fmt.Sprintf("%d:%d", p.Line, p.Column) }
+func (p *Position) Wrong() bool      { return p.Column == 0 }
+func (p *Position) LineIndex() int   { return p.Line - 1 }
+func (p *Position) ColumnIndex() int { return p.Column - 1 }

src/service/navigation/position_interval.go

@@ -0,0 +1,5 @@
+package navigation
+
+type Interval struct {
+	Start, Stop *Position
+}