Updated to build under MacOS as well.

MacOS has one slightly different name in the memory-mapped file interface.
Instead of MAP_ANONYMOUS, it defines MAP_ANON. So there's a #ifdef around the
two calls that use that, linking either the MAP_ANON or the MAP_ANONYMOUS
versions.
Removed DEBUG_LEVEL declaration from header debug.h

Variables should never be declared in header files. I moved the declaration
from the header file to the main file, and simply defined an extern int in the
header. This will allow other files to see the (global) variable, and even to
modify it, without raising a linker error if there are additional source
files.
Rearranging the project structure to match typical C project structure.

In a typical C project, source code is limited to the .c files. The .h files
are used for global definitions that must be shared between different source
files. I've taken the source code from the .h files and moved it into
corresponding src/*.c files. I've then created a (much smaller) .h file that
contains only the function prototypes and structure definitions.

There are probably still a bunch of unnecessary #include statements in both
the .c and .h files, but this is a good start.
Merge branch 'master' of github.com:JoshuaDavid/cpr

Revised venn.c to follow the same structure as the other two routines, moved
new source code into the updated sources.
Moved definition of DEBUG_LEVEL into commet_job.c.

This is a better place than in the main routines. This appears to be the only
place in the code where the value gets set to a non-zero value, so it seems
like the ideal place for it to live and for it to get initialized to a
zero-value as well.
Merge pull request #1 from phrodod/master

Rearrange project to follow standard C project syntax