Move no-mprime and no-mystery domain reformulations to subdirectory a…

…nd remove pathways-noneg. (#2)

README.md

@@ -1,7 +1,7 @@
 Fast Downward benchmark collection
 ==================================
 
-An inofficial collection of (sequential) IPC benchmark instances.
+An unofficial collection of (sequential) IPC benchmark instances.
 
 suites.py contains many predefined benchmark suites such as
 "optimal_strips", "satisficing", or "all". To obtain the
@@ -13,10 +13,21 @@ Please note that some IPC 2014 domains from the satisificing (sat)
 track were also used in the multicore (mco) and agile (agl) tracks.
 Please consult suites.py for the full domain lists of these two tracks.
 
-The collection contains some inofficial domain reformulations which we
-do not recommend for paper experiments:
+Notes on specific domains
+-------------------------
 
-  * no-mprime and no-mystery are copies of mprime and mystery but with
-    speaking predicate names.
-  * pathways-noneg is identical to pathways but without negative
-    preconditions.
+**mprime**: in contrast to the original mprime domain, our version forbids
+artificially generating additional fuel.
+
+Unofficial Reformulations
+-------------------------
+
+Under "unofficial-reformulations", we collect unofficial domain
+reformulations that are not recommended for paper experiments but have
+been useful for debugging purposes:
+
+  * mprime-renamed is a copy of mprime but with speaking predicate names.
+    Also, in mprime-renamed it is possible to artificially generate fuel
+    (as in the original IPC domain).
+  * mystery-renamed is a copy of mystery but with speaking predicate
+    names.