New Feature: added bmplog to debugger, closes #807

This creates an additional debugger window that lets you paste BitmapData objects in.

Usage:
FlxG.bmpLog.add(someBitmap);

You can use these console commands too:
clearBmp / clbmp -- clear all BitmapDatas in BitmapLog
clearBmpAt / clbmpat -- lets you specify index of Bitmap to clear. No argument or -1 means "the last one"
nextBmp / nbmp -- show the next BitmapData in the log's list
prevBmp / pbmp -- show the previous BitmapData in the log's list