Log received events on trace level

If you run moar with -trace you'll get all handled events listed after
moar finishes running.

The point would be to be able to debug mishandled keys as reported
in #55.

Also, remove the screen refresh timings from the trace logs. We get lots
of them, and I don't think they provide value any more.

m/pager.go

@@ -741,15 +741,15 @@ func (p *Pager) StartPaging(screen twin.Screen) {
 		event := <-screen.Events()
 		switch event := event.(type) {
 		case twin.EventKeyCode:
-			log.Trace("Handling key event...")
+			log.Tracef("Handling key event %d...", event.KeyCode())
 			p._OnKey(event.KeyCode())
 
 		case twin.EventRune:
-			log.Trace("Handling rune event...")
+			log.Tracef("Handling rune event '%c'/0x%04x...", event.Rune(), event.Rune())
 			p._OnRune(event.Rune())
 
 		case twin.EventMouse:
-			log.Trace("Handling mouse event...")
+			log.Tracef("Handling mouse event %d...", event.Buttons())
 			switch event.Buttons() {
 			case twin.MouseWheelUp:
 				// Clipping is done in _AddLines()

twin/screen.go

@@ -6,7 +6,6 @@ import (
 	"os"
 	"regexp"
 	"strings"
-	"time"
 	"unicode"
 	"unicode/utf8"
 
@@ -479,12 +478,7 @@ func (screen *UnixScreen) Show() {
 	}
 
 	// Write out what we have
-	t0 := time.Now()
-	byteCount := screen.write(builder.String())
-	t1 := time.Now()
-	dt := t1.Sub(t0)
-	megaBytesPerSecond := float64(byteCount) / (1024.0 * 1024.0) / dt.Seconds()
-	log.Trace("Wrote ", byteCount, " bytes to screen in ", dt, " at ", int(megaBytesPerSecond), "MB/s")
+	screen.write(builder.String())
 }
 
 func NewCell(rune rune, style Style) Cell {