add LED control function

Command-line to turn LEDs on the board on or off.

Also, modified .gitignore to be emacs-friendly.
add backlight control command to fernly

The command "bl" will set the backlight to a value from between 0
to a #define constant max brightness level.
initial take at LCD API

Nothing is correct at the moment, but basic commands are integrated
into the shell, which will simplifying merging later on for files
that are shared-edit.
add clock gating header file to fernvale
LCD turns on and draws.

Some basic progress on the LCD, such that the interface can
turn-on and draw.

The implementation uses a slow sequential-write method to update
the display; the vestiges of an auto-copy system are also in
place but not yet debugged.

The system seems to support two methods for issuing commands and
data to the LCD. One is a simple write-to-commit method. The
other is a more sophisticated command list that's set up, and
then dispatched. The write-to-commit kind of works now, although
it's left to be seen if we aren't running too far ahead of
commands or missing some wait states.

To get the demo to work, run the following commands in fernly:

bl 5  (turns on backlight)
lcd su   (sets up GPIOs and timing)
lcd init (initializes the LCD-side controller)
lcd tp1  (blasts a small test pattern to the top of display)

You'll note that the VCOM setting looks to be off (alternate
light/dark lines).

Next steps include:

1) verify that commands are being issued correctly to the LCD
(no missing commands due to writes happening faster than
the interface can keep up)

2) cross-check with LCD datasheet for the initialization
of the controller -- there are some undocumented commands
I left out in this implementation, maybe they need to go in
there; I also left out the gamma table.

3) get the autocopy method to work. I think, from what I can
tell, the autocopy will take a region of interest from memory,
composite it with up to four other regions with alpha blending,
and then auto-copy this to the LCD. You can insert commands
into the auto-copy stream as necessary, but I believe this,
combined with the TE (tearing effect) sync bit, will allow
you to just write to a region of memory as a frame buffer
and have it show up on the display without any CPU intervention.

Could be wrong tho....
main: Add firmware load/jump