Constructor. Makes children if depth of tree not reached
maxdepth yet
memUsage=JCSystem.getAvailableMemory(JCSystem.MEMORY_TYPE_PERSISTENT);
if(currDepth<maxDepth){
left=new ATreeNode((short)(currDepth+1),(short)maxDepth);
right=new ATreeNode((short)(currDepth+1),(short)maxDepth);
}