Job #19700 BUG: Crash in NodeBounds::draw() fixed.

QMap and QReadWriteLock are orthogonal. Combined them into a wrapper
class called NodeToJurisdictionMap, which replaces the typedef of the same name. This allows us to
avoid changing method signatures wherever NodeToJurisdictionMap is used.
The lock is bound with the map and is available to all clients of the
NodeToJurisdictionMap. The lock allows multi-threaded access to the map.

Changed usage of QMap::value to QMap::operator[] because the value method creates a temporary copy of the JurisdictionMap, whereas,  a reference is sufficient. This is more efficient and avoids a deep copy of the JurisdictionMap. 

Fixed compiler warning in NodeBounds.cpp regarding loss of precision
during conversion of double to GLfloat.