Kernal extensions

# Extensions of the included Kernal ROM

The included "Kernal ROM" has some improvements/changes as compared to an original C64 kernal:

- RAM at $fd30-$fd4f is not overwritten during reset
- Default device address is 8
- Default secondary address is 1
- Start and end address are displayed when loading
- C= key stops scrolling
- Faster key repeat
- Tape and RS232 routines removed
- Key commands:
  - F1 : `<CLS> LIST <CR>`
  - F2 : `SYS32768 <CR>`
  - F3 : `RUN <CR>`
  - F4 : `SYS4096*12`
  - F5 : `LOAD"`
  - F6 : `SAVE"`
  - F7 : `LOAD"$",8 <CR>`
  - F8 : `CLOSE7:OPEN7,8,15,"`
  - SHIFT-Run: `LOAD":*",8,1:RUN <CR>`
  - CTRL-D : Display directory of drive 8
  - CTRL-K : Read error channel of drive 8
  - CTRL-L : Load Basic program from RAM disk
  - CTRL-O : UNNEW
  - CTRL-U : Modifies the SAVE routine so that the RAM at $a000-$bfff can be `SAVE`d
  - CTRL-V : Swap Basic program with RAM disk
  - CTRL-W : Save Basic program to RAM disk
  - CTRL-X : Continue LIST command
  - CTRL-Z : Continue LIST command 50 lines earlier
  - CTRL-F1 : Swap screen with buffer 1
  - CTRL-F3 : Swap screen with buffer 2
  - CTRL-F5 : Swap screen with buffer 3
  - CTRL-F7 : Swap screen with buffer 4
  - CBM-F1 : Write screen to buffer 3
  - CBM-F3 : Write screen to buffer 4
  - CBM-F5 : Get screen from buffer 3
  - CBM-F7 : Get screen from buffer 4
- Startup message shows "BASIC X2"