Add "Additional Scripts" section to IGB Scripting page in User's Guide

We should add an "Additional Scripts" section to the IGB Scripting page in User's Guide:

https://wiki.transvar.org/display/igbman/Track+lines+for+configuring+track+appearance

Also add text stating that "More scripts will become available in the near future!"

Here's a list of all the currently available commands (some are already discussed in the User's Guide) -

genome
goto
loadAllows multiple files to be specified, split by commas
loadfromserver
loadmode
print
refresh
selectAllows multiple gene ids to be specified, split by commas
selectfeature
sleep
sidetrackAllows multiple files to be specified, split by commas
showtrackAllows multiple files to be specified, split by commas
snapshot
snapshotwholeFrame
snapshotmainView
snapshotmainViewWithLabels
snapshotslicedViewWithLabels
homescreen
bringToFront