Refactor tabpane

- Move from termui/extra/tabpane.go to termui/tabpane.go
- Renamed from Tabpane to TabPane

_examples/tabs.go

@@ -8,7 +8,6 @@ package main
 
 import (
 	ui "github.com/gizak/termui"
-	"github.com/gizak/termui/extra"
 )
 
 func main() {
@@ -24,7 +23,7 @@ func main() {
 	header.Border = false
 	header.TextBgColor = ui.ColorBlue
 
-	tab1 := extra.NewTab("pierwszy")
+	tab1 := ui.NewTab("pierwszy")
 	p2 := ui.NewParagraph("Press q to quit\nPress h or l to switch tabs\n")
 	p2.Height = 5
 	p2.Width = 37
@@ -33,7 +32,7 @@ func main() {
 	p2.BorderFg = ui.ColorYellow
 	tab1.AddBlocks(p2)
 
-	tab2 := extra.NewTab("drugi")
+	tab2 := ui.NewTab("drugi")
 	bc := ui.NewBarChart()
 	data := []int{3, 2, 5, 3, 9, 5, 3, 2, 5, 8, 3, 2, 4, 5, 3, 2, 5, 7, 5, 3, 2, 6, 7, 4, 6, 3, 6, 7, 8, 3, 6, 4, 5, 3, 2, 4, 6, 4, 8, 5, 9, 4, 3, 6, 5, 3, 6}
 	bclabels := []string{"S0", "S1", "S2", "S3", "S4", "S5"}
@@ -47,12 +46,12 @@ func main() {
 	bc.NumColor = ui.ColorYellow
 	tab2.AddBlocks(bc)
 
-	tab3 := extra.NewTab("trzeci")
-	tab4 := extra.NewTab("żółw")
-	tab5 := extra.NewTab("four")
-	tab6 := extra.NewTab("five")
+	tab3 := ui.NewTab("trzeci")
+	tab4 := ui.NewTab("żółw")
+	tab5 := ui.NewTab("four")
+	tab6 := ui.NewTab("five")
 
-	tabpane := extra.NewTabpane()
+	tabpane := ui.NewTabPane()
 	tabpane.Y = 1
 	tabpane.Width = 30
 	tabpane.Border = true