In progress: re-writing whole program.

I wanted to add the capability to save the image WCS information to
the output postage stamps of TIFAA. But then I noticed I can also add
a multi-thread option and I noticed that the whole management of TIFAA
(being one of the first programs I wrote) is very primitive. So I
began the job of re-writing it based on my new methods while also
adding the two mentioned capabilities.

Currently the user-interface (in ui.c and ui.h) is complete.
Re-written old algorithm.

The old algorithm is now completely re-written based on the pthreads,
the only problem is that wcslib uses a non-thread-safe method to parse
through the headers and so, I had to put a mutex on that part of the
code that slows down the job when more threads are used!!! But it
still works fast when only one thread is used.

I hope wcslib uses a thread-safe method soon.
WCS coordinates added, information included in FITS header.

The main update now is that every output FITS image has WCS
information in it, activating RA and Dec information for all its
pixels.

I also added some comments to the FITS header that will tell the
reader what RA and Dec were used to create this postage stamp, along
with the postage stamp size and resolution.

The README file was also updated.