variable grid size seems to work...
Made a minor change to allow mergedx2 to allocate more than 4GB of memory.  Also got rid of some magic numbers, and fixed the option parsing mess.
Updated to allow more input files.  Also fixed new addressing problem that was causing a segfault during memory writes.
Added a simple comment to indicate progress, and maybe help with debugging.
Changed a few 'int's to 'size_t'.  Hopefully this will take care of the issue.  I don't have enough memory to test it on Lane's file though.
Changed the type of a variable, 'u', used as an index.  It's not clear why it's used instead of the IJK macro, which is otherwise used extensively.
I went over vgrid.c very carefully and changed any variable that looked like it could everflow to type size_t.
Changed printf format string to print unsigned longs where appropriate.  Also updated the dx file reading code to use the extra big storage.
Yet another integer overflow bug in mergedx2 bug squashed.
Fixed two problems in vgrid.c.  One had to do with verifying the size of the grid, and the other a memory allocation error.  I also fixed an error in the interpolation code when resizing a grid with mergedx2.  All errors only occur with grids containing more than 2^32 points.
Minor change to library ordering to support Ubuntu's (and other distros) default linker flag '--as-needed'.
Merge remote-tracking branch 'origin/master' into monson-dev