Move catch for function recursion detection.

Catching this at ModuleInstantiation::evaluate() should ensure the whole
function call is terminated with the first exception. Otherwise function
calls with multiple recursion points (e.g. function f(x) = f(x) + f(x);)
will still descent into the recursion multiple times.

src/context.cc

@@ -162,6 +162,14 @@ bool Context::has_local_variable(const std::string &name) const
 	return variables.find(name) != variables.end();
 }
 
+/**
+ * This is separated because PRINTB uses quite a lot of stack space
+ * and the methods using it evaluate_function() and instantiate_module()
+ * are called often when recursive functions or modules are evaluated.
+ * 
+ * @param what what is ignored
+ * @param name name of the ignored object
+ */
 static void print_ignore_warning(const char *what, const char *name)
 {
 	PRINTB("WARNING: Ignoring unknown %s '%s'.", what % name);

src/evalcontext.cc

@@ -27,12 +27,7 @@ ValuePtr EvalContext::getArgValue(size_t i, const Context *ctx) const
 	const Assignment &arg = this->eval_arguments[i];
 	ValuePtr v;
 	if (arg.second) {
-		try {
-			v = arg.second->evaluate(ctx ? ctx : this);
-		}
-		catch (RecursionException &e) {
-			PRINT(e.what());
-		}
+		v = arg.second->evaluate(ctx ? ctx : this);
 	}
 	return v;
 }

src/module.cc

@@ -153,8 +153,13 @@ AbstractNode *ModuleInstantiation::evaluate(const Context *ctx) const
 	PRINT("New eval ctx:");
 	c.dump(NULL, this);
 #endif
-	AbstractNode *node = ctx->instantiate_module(*this, &c); // Passes c as evalctx
-	return node;
+	try {
+		AbstractNode *node = ctx->instantiate_module(*this, &c); // Passes c as evalctx
+		return node;
+	} catch (RecursionException &e) {
+		PRINT(e.what());
+		return NULL;
+	}
 }
 
 std::vector<AbstractNode*> ModuleInstantiation::instantiateChildren(const Context *evalctx) const