autotools (for C impl.), change name to cm

This is a WIP, it makes much more sense to have an autotools process, makes it easier to integrate and use.

This already builds stmd, more rules are required in makefile. Advise to move deployment away from makefile "update site" doesn't belong here.

I'll do library stuff and debugging and some configure switches and whaever, if you're going to merge.

There is much work to be done on this C implementation before we can build a library and use it.

Included is rename in all places that are C to cm.
Note that this assumes that you have a C compiler that supports `gcc`-like options.  That is most C compilers these days, but it's a little non-autoconfy to assume that you have gcc.

You can use a macro like [AX_CHECK_COMPILER_FLAGS](http://ac-archive.sourceforge.net/ac-archive/ax_check_compiler_flags.m4) to check whether given flags are valid.