Updated .gitignore

Added .dat, .txt, and inputGen* files to the gitignore, as they
are related to testing and are not a part of the project itself.
Updated Makefile

Updated compiler flags to use the C99 standard instead of C89. This
was in order to get rid of some compiler errors and warnings which
broke the build under C89.
Commented source files.

Added comments to all the source files.
fixes
Added license

Licensed the project under the WTF Public License.
Merge branch 'develop'