Mention corresponding starter for most of the things

This should handle quotes, parens, brackets, subscripts and many other
things.

Resolves part of RT #125641.

Unfortunately I don't know how to print the actual starter, but as
long as the line number is mentioned it's alright.

src/Perl6/Grammar.nqp

@@ -255,7 +255,8 @@ role STD {
         $stopper := $stopper // $goal;
         $stopper := $stopper ~~ /(.*\S)\s*/;
         $stopper := ~$stopper[0];
-        self.typed_panic('X::Comp::FailGoal', :$dba, :goal($stopper));
+        self.typed_panic('X::Comp::FailGoal', :$dba, :goal($stopper),
+                         :line-real(HLL::Compiler.lineof(self.orig(), self.from())));
     }
 
     method panic(*@args) {

src/core/Exception.pm

@@ -766,10 +766,12 @@ my class X::Comp::AdHoc is X::AdHoc does X::Comp {
 my class X::Comp::FailGoal does X::Comp {
     has $.dba;
     has $.goal;
+    has $.line-real;
 
     method is-compile-time(--> True) { }
 
-    method message { "Unable to parse expression in $.dba; couldn't find final $.goal" }
+    method message { "Unable to parse expression in $.dba; couldn't find final $.goal"
+                     ~ " (corresponding starter was at line $.line-real)" }
 }
 
 my role X::Syntax does X::Comp { }