Simplify Flux catch handlers. (#421)

All `RecognitionException`s are finally caught in the `flux` catch handler which can then take the appropriate measures.

Author: blackwinter

metafacture-flux/src/main/antlr/org/metafacture/flux/parser/Flux.g

@@ -61,9 +61,6 @@ varDef
       ^(ASSIGN Identifier exp)
   ;
 catch [RecognitionException re] {
-    reportError(re);
-    recover(input,re);
-    retval.tree = (CommonTree)adaptor.errorNode(input, retval.start, input.LT(-1), re);
     throw re;
 }
 
@@ -77,9 +74,6 @@ flow
   '|'! flowtail ('|'! Wormhole)? ';'!
   ;
 catch [RecognitionException re] {
-    reportError(re);
-    recover(input,re);
-    retval.tree = (CommonTree)adaptor.errorNode(input, retval.start, input.LT(-1), re);
     throw re;
 }