Write a schematic for the contains function

Should retrieve the nodes below a requested address, this operation will
be important.
Try a naive approach for the contains (or maybe subtree) function
Fix warning messages on cray
Merge branch 'master' into contains
Fix and carefully test the contains function
Remove unnecessary calls to the preorder_label function, use geom struct
Fix a major bug in the tree_size_atlevel macro, causing duplicate PL's

The macro was exceeding the maximum integer value. Solution is easy,
just cast something inside the expression to int64.
Check for in-bounds address in contains function
Put the rabview program back in the Makefile, and add an rnp_max macro
Prepare 1d hydro to use new gradient estimation, at 1st order for now