Enhanced capabilities given to the build script

Code in the GramSchmidt.sh script was modified to allow 'make' statements to be
redirected to files for stdout and stderr, while also having stderr printed to
the screen.

More testing is also being done with the export-subst attribute.

File: Build/GramSchmidt.sh
--------------------------
- Cleaned up the 'release' section
- Added new environment variables for the documentation and release directory
  paths
- Redirect stdout and stderr to files from the 'make' commands, while also
  printing stderr to the screen

File: Doxyfile
--------------
- Changed the OUPUT_DIRECTORY tag to use the new environment variable for the
  documentation directory path

File: README
------------
- Add an export-subst string to test that it does NOT get expanded