if < 1 GB do not auto-enable ccache
if < 5 GB warn about debug/symbol build

i.e. add the missing api directly to ServerFont

but such (optional) sub-nodes should be handled explicitly when
handling the node (e.g. optional subscript)

HandleNodes() -> HandleNode(), as it just handle the one node
 (and children recursively)
add HandleAllSubNodes() to handle all children of a node
there seem to be no point in checking GetSubNode() for NULL, as it
 seems it can't be so

It seems that it doesn't read characters unless the font is explicitly
specified as "Cambria Math"