Aipy

* Added support to mdlvis.py for simulating data without an input UV file.
* Added "none" mode to xrfi.py to flag only those channels specified manually.
* Added line to alm_wrapper.cpp to support compilation on python < 2.5.

* Changed modmap.py to work with sources of nonzero angular size. Also added
support for changing the data type (double,float) of a map.
* Added parameter to mk_img.py to control minimum altitude to allow for
phase center. Also added parameter for resuming interrupted faceting.
* Fixed xrfi.py default parameter "intthresh" to avoid excessive flagging
of integrations.
* Made fitmdl.py skip fitting when there are no data. Added "snap" mode to
fit parameters every integration.
* Added text color option to plot_map.py
* Added ionospheric refraction code using 1/freq**2 scaling. This involved
some significant refactoring of code, and some changes in fitmdl.py and
mdlvis.py.
* Changed fitmdl.py to cache UV data, resulting in less time reading files.
This significantly sped up code, although may become problematic with
fits involving lots of data.
* Removed some per-baseline computations in ant.py that occured every
compute, even if unnecessary. Baseline projections are now computed as
needed. Sped up simulations involving few baselines.
* Bugfix to miriad "select" command involving "time" selection: double
arguments were incorrectly cast as floats.
* Made mk_map.py a little more efficient in calculating map weights.

* Changed how loc-specific source parameters are implemented (now with
get_catalog() instead of src_prms). Changed scripts to use this format,
and scripting.parse_srcs() to return values that can feed get_catalog().

* Built in decimation to UV files in miriad_wrap.cpp.
* Added decimation selection with select() to UV files in miriad.py.
* Bugfix on various scripts to use new clean command.

* Split out cleaning functionality from mk_img.py into cl_img.py.
* Added snapshot capability to mk_img.py
* Bugfix for plot_img.py grid being upside-down.
* Reimplemented clean in C for speed.

* Added resolving support for elliptical sources in resolve_src() in ant.py.
* Reworked how get_baseline() and gen_uvw() functioned to facilitate elliptical
sources. This change required updating scripts that use gen_uvw().
* Allowed specifying coordinate epochs for RadioFixedBody's
* Changed how plot_img.py, mk_map.py work. There is now a general script
mk_img.py which geberates FITS files (introduced in 0.7.1) for each specified
source, or for equally-spaced phase centers around the sphere. This script
is responsible for all image generation. mk_map.py now takes these FITS
images as input and uses them as facet images to make a spherical Healpix
map. plot_img.py is now a visualization tool (a la plot_uv.py and
plot_map.py), and overlays appropriate ra/dec grids on the FITS images.
* Flipped u/v order (and sign of v) in the Img class in img.py to be more
naturally compatible with FITS image conventions. Required a change to
Img.gen_LM() as well.