Fix crash on "endofscreen" clearing

[damienalexandre]

I got this error while trying to clear a screen from cursor to the end:

Uncaught TypeError: this.vdu.cursorToEndOfScreen is not a function
    clear http://www.minipavi.fr/emulminitel/library/minitel/decoder.js:354
    decode http://www.minipavi.fr/emulminitel/library/minitel/protocol.js:388
    decodeList http://www.minipavi.fr/emulminitel/library/minitel/protocol.js:409
    <anonymous> http://www.minipavi.fr/emulminitel/library/generichelper/generichelper.js:63
    decodeList http://www.minipavi.fr/emulminitel/library/minitel/protocol.js:408
    sendChunk http://www.minipavi.fr/emulminitel/library/minitel/minitel-emulator.js:293
    timer http://www.minipavi.fr/emulminitel/library/minitel/minitel-emulator.js:246

The function exists it's just in another object.

Also, thanks a lot for this project!