feat(pagination): implement paginated output

Implement a `pager` config option. If configured, `cheat` will
automatically pipe output through the configured pager (where
appropriate).

cmd/cheat/cmd_view.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/cheat/cheat/internal/config"
+	"github.com/cheat/cheat/internal/display"
 	"github.com/cheat/cheat/internal/sheets"
 )
 
@@ -47,5 +48,5 @@ func cmdView(opts map[string]interface{}, conf config.Config) {
 	}
 
 	// display the cheatsheet
-	fmt.Print(sheet.Text)
+	display.Display(sheet.Text, conf)
 }