Merge pull request #1 from westie314/doxygen_comments

Add prototypical Doxygen tags to comments for function extraterrestrial_radiation
Update .gitignore
Remove Doxygen-generated files; add *.htm header and footer
Add Doxygen comments to source
Update Mac OSX make scripts following OS upgrade
Rework CMake files to allow compilation on Mavericks
Merge remote-tracking branch 'upstream/master'
Merge pull request #9 from westie314/master

Modify CMake files for Mac OSX; modify Doxygen comments.