Convert the project to use the GNU Build System (aka Autotools)

LICENSE was renamed COPYING because otherwise `autoreconf` complains loudly.
This is also the reason AUTHORS, INSTALL, and README were created.

Man pages were moved into src/pam_panic/man and src/pam_panic_pw/man.

Finally, certain variables are passed through the config.h file to the
module rather than as -D flags on the command-line.

.gitignore

@@ -0,0 +1,16 @@
+*.la
+*.lo
+*.o
+.deps
+.libs
+aclocal.m4
+autom4te.cache/
+build-aux/
+config.h
+config.log
+config.status
+configure
+libtool
+Makefile
+Makefile.in
+src/pam_panic_pw/pam_panic_pw