Updated build system

By request I've moved the build system to use automake and autoconf. This is a change from the previous system that used autoconf to modify hand-written Makefiles. This should make the library feel a bit more like other projects in terms of familiar targets and build procedures. I expect a v1.3 release in the not too distant future that will include this, along with some code updates. Until then, check out the version residing in the git repository if you are curious to try it out.