_defaultChar_t consideration

[todo]

this test might bring the consideration to return/have something different

---

sdl2-vga-terminal/sdl2-vga-terminal/test/tests.cpp

Lines 148 to 153 in a072502

	// TODO _defaultChar_t consideration
	// BODY this test might bring the consideration to return/have something different
	// rather that {0, 0, 0} when wrong input for .at
	std::string title = ::testing::UnitTest::GetInstance()->current_test_info()->name();
	VgaTerminal term = VgaTerminal(title, SDL_WINDOW_HIDDEN, -1, 0);
	SDL_Rect vp = term.getViewport();

---

This issue was generated by todo based on a TODO comment in a072502 when #111 was merged. cc @Raffaello.