ptMon-All: generalized a bit

Removed full path call of gnuplot, pushing that responsibility to caller.
So, I also added a checks to make sure gnuplto and other called scripts
are in the PATH.
mkRIN: mktemp for better temporary files

Implemented a real temporary directory with mktemp.  Also, adjusted the
trap on exit to remove this directory.
mkRIN: minor syntax change
mkRIN: mtime control (sbfExtract() only)

If mkRINEX... ran immediately after download, it wouldn't need to
manipulate file timestamps.  But, currently, there is a back log, and
I've never autmated it.

And, it's only useful if you want to use timestamps to find SBF
extracted data.  But, I want to do this, now, to make the plotting tools
for the PT monitoring website.

So, In order to make modification times useful, I've added a mtime
manipulation code so that mkRIN preserves the modification time of the
SBF binary files *as* the mtime of the extracted data files (and their
compressed archive files in organizedData/).

In addition, this code adds a storage subroutine called by sbfExtract()
which contains the new logic.

But, this only works for sbfExtract() which is currently only used for
GLOTime extraction.  I think I will replace the other functions, since
doing so now has extra benefit.
mkRIN: extaction subs -> sbfExtract (INCOMPLETE)

Converted all calls to the old extraction subroutines into calls to
sbfExtract.  This required updates of many global variables.

Also, this is not a complete patch.  The next patch is also required,
but it conflicts with other branches, be careful.
mkRIN: generalized most everything

The previous version was running fine, but required different hard coded
configuration values to run on my test computer.  So, I finally had to
rewrite all of the configuration code.

This commit assumes all externals are in the PATH and implements checks
for all the ones that don't live in /usr/bin.  It also has some extra
debugging lines, performs multiple checks before raising errors, and
runs in a real mktemp temporary directory while maintaining the ability
to specify run-time options using relative paths.