rename FITSIO.jl -> cfitsio.jl
new FITSIO.jl with just exports and includes
add doc/_build to gitignore
add fits_copy_image_section
add finalizer to FITSFile; fits_assert_open()
add hdutype, imagetype, imagedim functions
add fits_read_subset()
add start of high-level interface

Conflicts:
	src/FITSIO.jl
remove fitsread() function
docs: high-level interface example
enable rw mode
make all supported image types round-trip
add test script
add header functions for FITS type
add to docs on high-level interface