Allow chaning of touchpad sensitivity in the System settings menu. Some
units are dodgey at "Normal" senitivity and some at "High". "High" can make
some units difficult to navigate and may even require a settings reset so try
it and don't use "High" again if it doesn't work out :-). Defaults to "Normal"
which behaves like older builds.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17656 a1c6a512-1295-4272-9138-f99709370657
