Latvian: added support for double negation, fixed some structural words

Double negation: sebject-dependent - works, object-dependent - still has to be fixed (in VerbsLav).
Structural words: everybody, somebody, nobody.
Both motivated by AttemptoLav.

lib/src/latvian/SymbolLav.gf

@@ -9,6 +9,7 @@ flags
   coding = utf8 ;
 
 lin
+
   SymbPN i = {s = \\_ => i.s ; g = Masc ; n = Sg} ;
   IntPN i  = {s = \\_ => i.s ; g = Masc ; n = Pl} ;
   FloatPN i = {s = \\_ => i.s ; g = Masc ; n = Pl} ;
@@ -16,16 +17,21 @@ lin
 
   CNIntNP cn i = {
     s = \\_ => cn.s ! Indef ! Sg ! Nom ++ i.s ;
-    a = agrgP3 Sg cn.g
-    } ;
+    a = agrgP3 Sg cn.g ; 
+    isNeg = False
+  } ;
+
   CNSymbNP det cn xs = {
     s = \\_ => det.s ! cn.g ! Nom ++ cn.s ! det.d ! det.n ! Nom ++ xs.s ;
-    a = agrgP3 det.n cn.g
-    } ;
+    a = agrgP3 det.n cn.g ;
+    isNeg = False
+  } ;
+
   CNNumNP cn i = {
     s = \\_ => cn.s ! Indef ! Sg ! Nom ++ i.s ! Masc ! Nom ;
-    a = agrgP3 Sg cn.g
-    } ;
+    a = agrgP3 Sg cn.g ;
+    isNeg = False
+  } ;
 
   SymbS sy = sy ;
 
@@ -37,6 +43,7 @@ lincat
   Symb, [Symb] = SS ;
 
 lin
+
   MkSymb s = s ;
 
   BaseSymb = infixSS "un" ;