* sr22-set.xml: add tags.
* Models/Interior/Panel/Instruments/asi/asi.xml: display airspeed correctly under 120 knots.
* sr22-yasim.xml: the nose wheel is castering, not steerable.
* Systems/sr22-keyboard.xml, Systems/help.xml: use Shift+L for landing light, so that L
locks/unlocks the castering nose wheel, which is the default binding. Document.
* Systems/views.xml: add type="double" to default-field-of-view-deg so that model view works.
