Handle empty RRF files, add MTS2012AB

diff --cc sql.lisp
index dab38b8ba2d29bb059cacf073ca6fbcd23a0cf0b,32cc98d55c5c2bbdec776000392fb1962ba9d063..3847d02492692f4d5da0c2ee85f87b0be93a937e
--- 1/sql.lisp
--- 2/sql.lisp
+++ b/sql.lisp
@@@ -21,9 -21,10 +21,9 @@@
        (:2006ac . "KUMLS2006AC")
        (:2006ad . "MTS2006AD")
        (:2009ab . "MTS2009AB")
 -      (:2010aa . "MTS2010AA_ALL")
 -      (:2011aa . "UMLS2011AA")
 -      (:2012aa . "MTS2012AA_ALL")))
 +      (:2010aa . "MTS2010AA")
 +      (:2012ab . "MTS2012AB")))
- (defvar +default-umls-db+ "MTS2012AB")
+ (defvar +default-umls-db+ "MTS2012AA_ALL")
  
  (defun lookup-db-name (db)
    (cdr (assoc (ensure-keyword db) +umls-sql-map+)))