Position management code implemented and tested

CHANGED: POSITIONMANAGER.CS; Set and Change position call one function.
ADDED: POSITIONLIMITMANAGER.CS; CheckOrderLimit(), create limit if missing.
CHANGED: POSITIONLIMITMANAGER.CS; SetPositionLimit(), uses XPath.
CHANGED: POSITIONLIMIT.CS; CheckRules() debugged, now returns string array.
CHANGED: POSITIONLIMIT.CS; SetPositionLimit(), returns bool, handles root.
ADDED: POSITIONLIMIT.CS; HasLimit() fn, DefaultRestrictionLimit() fn
FIXED: POSITIONDAL.CS; Missing comma
FIXED: POSITIONLIMITHISTORYDAL.CS; Unquoted string fixed.
CHANGED: POSITION.CS; Copy ctor adapted to handle null right-hand-side
ADDED: EXTENSIONS.CS; Ascii functions
CHANGED: TableCreate scripts; Foreign keys removed.