Changes the MyView class to make the app fastser

1 Change the MyView class to a extend of ImageView and no longer
runnable or static
2 Add a HandWriting class to paint the locus(gui ji)
3 Need to use another algorithm to smooth the locus
4 known bug: when you used the app for several times, this bug may
happen in a
"myView.mCanvas.setBitmap(myView.background)" method.Copying the bmp
files again to overwrite the existing files can make it solved.(don't
know why)