cosmoV_throw() now resets the vm stack as well

also a minor GC bug in cosmoO_newError was fixed.

i'm going to try to phase out cosmoM_freezeGC & friends
since that would cause hell with this new
error handling solution. the only thing still using it is the GC.

src/cstate.h

@@ -43,6 +43,8 @@ typedef struct ArrayCObj
 typedef struct CPanic
 {
     jmp_buf jmp;
+    StkPtr top;
+    int frameCount;
     struct CPanic *prev;
 } CPanic;