Change spiderT format to remember isNVV status

[rtmclay]

The current format of spiderT does not remember NVV status for each directory entry in MODULEPATH. This means that it needs to checked again when building ModuleA from spiderT.

Whether this should be done or not depends on how slow it takes to recalculate the NVV status. The time it takes will be linear in the number of shortnames (sn) in a moduleTree.