Sky map overlap integral can now use MOC (multi-ordered) GW sky maps; fixes #19

This MR adds the ability to handle multi-ordered (MOC) sky maps, compared to be only able to use flat sky maps before. In addition, can handle single pixel secondary sky maps (as would be applicable for Swift, since the localization is on the order or less than a single pixel).

This MR enables the ability to handle the following combinations of sky maps:

1. MOC-MOC
2. MOC-flat
3. flat-flat (previous method)
4. MOC-ra/dec
5. flat-ra/dec

Bin scripts have been updated with these new options.

Appropriate unittests were added to verify these methods give identical results.

These changes were also tested and verified with Gracedb Events (e.g. https://gracedb-playground.ligo.org/superevents/S220317ch/view/).

ligo/raven/search.py

@@ -210,12 +210,12 @@ def skymap_overlap_integral(se_skymap, exttrig_skymap=[], se_skymap_uniq=[],
         doi.org/10.3847/1538-4357/aabfd2
     while the flattened sky map version was mentioned:
         https://git.ligo.org/brandon.piotrzkowski/raven-paper
-        
+
     Either a multi-ordered (MOC) GW sky map with UNIQ ordering,
     or a flattened sky map with Nested or Ring ordering can be used.
     Either a flattened external sky map with Nested or Ring ordering,
     or a position indicated by RA/dec can be used.
-    
+
     Parameters
     ----------
     se_skymap: array
@@ -262,8 +262,8 @@ def skymap_overlap_integral(se_skymap, exttrig_skymap=[], se_skymap_uniq=[],
             # Use multi-ordered gw sky map and one external point
             # Relevant for very well localized experiments
             # such as Swift
-            c = SkyCoord(ra = ra * u.degree, dec = dec * u.degree)
-            catalog = SkyCoord(ra = ra_gw, dec = dec_gw)
+            c = SkyCoord(ra=ra*u.degree, dec=dec*u.degree)
+            catalog = SkyCoord(ra=ra_gw, dec=dec_gw)
             ind, d2d, d3d = c.match_to_catalog_sky(catalog)
 
             skymap_overlap_integral = \