Vixen StarBook control

Control a Vixen SX telescope mount StarBook

STARBOOK: a class to control the Vixen StarBook for telescope mounts.
StarBook, StarBook S and StarBook Ten are supported, to control
SX, SX2, SXD2, SXP, SXW, SXD and AXD mounts.
The mount should have been aligned and configured (date, location,
weighting)) before, and the StarBook IP should be read accessing the
'About STAR BOOK' menu item.
Then use e.g.:

sb = starbook('169.254.1.1');

to establish the connection and display the StarBook screen.

The buttons are active in a similar way to the physical ones. The mouse
wheel allows to zoom in/out, and the display is regularly updated (5 sec).
You can access more actions from the top menu, and unactivate the
auto-update.

For testing purposes, you may open a simulated StarBook with:

sb = starbook('simulate');

or use 'simulate' as IP in the input dialogue.

Methods:
starbook(ip): connect to a StarBook controller
gotoradec(sb, ra, dec): send StarBook to RA/DEC
move(sb, n,s,e,w): move the SB in given direction. Use stop to abort.
align(sb): align current coordinates to RA/DEC target
stop(sb): stop the mount (e.g. during move/gotoradec)
setspeed(sb): set the current zoom/mount speed 0:stop - 8:fast
image(sb): display the StarBook image (only for 320*240 screen)
home(sb): send the SB to its HOME position
help(sb): open the Help page
grid(sb): prepare a grid around target

Other minor commands
start(sb): set/reset the StarBook in SCOPE mode
getspeed(sb): return the current zoom/mount speed
getstatus(sb): update the StarBook state
getxy(sb): update motor coders
getscreen(sb): get the StarBook image as an RGB matrix
update(sb): update status and image
plot(sb): same as image(sb)
close(sb): close the screen view
web(sb): show the current target on sky-map.org
zoom(sb,{z}): get/set the zoom level. z can be 'in','out' or in 0-8
date(sb): get the starbook date/time
chart(sb): open skychart (when available)

Credits:
urldownload : version 1.0 (9.81 KB) by Jaroslaw Tuszynski, 23 Feb 2016
https://fr.mathworks.com/matlabcentral/fileexchange/55614-urldownload

rubytelescopeserver: Rob Burrowes 2013
https://github.com/rbur004/rubytelescopeserver

(c) E. Farhi, GPL2 - version 18.08.10