Uses the sphinxcontrib-spelling extension and requires PyEnchant and
aspell-en to be installed.

Adds the optional make target 'spelling' which produces the file
spelling/output.txt. It contains all words it detects.

Due to the large number of false positives, words in
utils/sphinx-config/false_positives.txt are ignored.

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15668 f3b2605a-c512-4ea7-a41b-209d697bcdaa

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15621 f3b2605a-c512-4ea7-a41b-209d697bcdaa

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15617 f3b2605a-c512-4ea7-a41b-209d697bcdaa

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15590 f3b2605a-c512-4ea7-a41b-209d697bcdaa

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15561 f3b2605a-c512-4ea7-a41b-209d697bcdaa

(cherry picked from commit 79e867c213ee022685e5bb8a5089a112099e4f06)

(cherry picked from commit 4629a464f701f919633fd220860b6610d097c291)

(cherry picked from commit 453521c8e682c6563226dfcc57c689052dacd21f)

(cherry picked from commit 7cb39811d47b1f364286597acea21c3afd010733)

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15533 f3b2605a-c512-4ea7-a41b-209d697bcdaa

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15518 f3b2605a-c512-4ea7-a41b-209d697bcdaa

On MacOS X there is no sha1sum. So to simplify doc generation on those systems
use a Python script instead to generate a unique string from the repository
path.

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15137 f3b2605a-c512-4ea7-a41b-209d697bcdaa

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@15103 f3b2605a-c512-4ea7-a41b-209d697bcdaa

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@14981 f3b2605a-c512-4ea7-a41b-209d697bcdaa

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@14950 f3b2605a-c512-4ea7-a41b-209d697bcdaa