.gitignore: update
configure.ac: restructure MIRIAD checks; work with binary packages

Attempt to make it so that we can build against a MIRIAD binary package. This
actually doesn't work out of the box on Linux, but it works on Macs.
configure.ac: clean up numpy includedir check a little bit
configure.ac: bump to 1.2.4
miriad.py: fix warning from Sphinx
Update web and README