Gmt module: Base2Something raise error flag if initialized by pointer of incompatible type.

Some small changes.

modules/gmt/modgmt_func.cpp

@@ -22,7 +22,11 @@ class Base2Something: public OBTypeM<Func,O...>
  Base2Something(const ObjectBase* arg):OBTypeM<Func,O...>(arg) {};
  Base2Something(const ObjectList* input, const std::string& name):OBTypeM<Func,O...>(input->Get(name)){};
  Base2Something(const ObjectList* input, const ObjectList::ListValues::size_type i):OBTypeM<Func,O...>((i<input->Size())?input->At(i):0){}; // Check index, because At is not safe
- auto operator ()(bool* b) const -> decltype(this->OBTypeM<Func,O...>::template operator()<bool*>(b)) {return OBTypeM<Func,O...>::operator ()(b);}
+ auto operator ()(bool* b) const -> decltype(this->OBTypeM<Func,O...>::template operator()<bool*>(b))
+ {
+  if(!OBTypeM<Func,O...>::operator bool()) *b=false;
+  return OBTypeM<Func,O...>::operator ()(b);
+ }
 };
 
 // Converting Int, Real or String to double
@@ -226,8 +230,7 @@ class ProjConv<ObjectList>
    if(proj) return p=proj->Data(); // Case 1
    OBType<ObjectList> list(arg);
    if(list) return p=operator()(list,issuc); // Case 2
-   *issuc=false;
-   return p; // Conversion failed
+   goto fail; // Conversion failed
   }
 
   // Case 3
@@ -834,8 +837,7 @@ ObjectString can be number or in form "dd:mm[:ss]", where dd is degrees from -36
 ObjectBase* GMT_Coord(const ObjectList* input)
 {
  if(input->Size()!=1) return 0;
- const ObjectBase *arg=input->At(0);
- Base2Coord a(arg);
+ Base2Coord a(input,0);
  struct gmt_coord c;
  bool suc=true;