netset KTech library update review

[TheRealKaup]

I'm rewriting netset, the KTech game I'm developing, to work with the latest version of KTech, because since the previous version which was used by netset, KTech has seen too many changes to simply update code using it.

This issue will serve to list limitations encountered.

• Texture::SetBackgroundAlpha() and Texture::SetForegroundAlpha(). #61
• Memory::CallOnTicks() doesn't call for UIs and Widgets. #62
• Texture::Resize()'s CellA newValue should have a default argument. #63
• Missing texture pattern placed for cases in which Texture::File() failed. #64
• UI::Render() and Camera::Render() should add foreground color regardless of the character (as in, now it doesn't if the character is a space). #65
• Widget::shown #66
• Missing easy way to create nested Widgets. There should be Widget::parentWidget and Widget::childWidgets, which will be used to create a chain of calls when Select(), Deselect(), Show() and Hide() are called. These chains should consider state machines. #67
• Conventions #68
• Separate Memory::Container definitions from memory.cpp to container.cpp. #69
• Merge container.cpp into container.hpp - container.cpp is not included within game projects, and is only used to explicitly instantiate KTech structures, which blocks Container from being easily used from outside. #74
• Container::operator[] segfaults if it's empty #80
• Widget::OnSelect(), OnDeselect(), OnShow() and OnHide() rather than RenderSelected() and RenderUnselected() virtual functions. #81
• Widgets should remove themselves from parent's vector on destruction #82
• Widgets SetText() and SetValue() #83
• Adding the same structure to a parent structure twice by accident will cause a segfault at quit #84
• Texture::ExportToFile() is broken as it hasn't been updated to function with the new CellA members composition #85
• IntField::ChangeValue() is broken; Texture::Simple() is used rather than Texture::Rectangle() to reset the value text. #86
• If Texture::File() fails, it returns UPoint(0, 0) instead of UPoint(2, 2) like it should, or perhaps just GetSize(). It also only resizes m_t and doesn't clear it like it should, as not doing so will keep old cells. #87
• Engine::Engine() is missing inline, and there is no Engine::Quit() that simply sets running to false. #88
• Input::CallbacksGroup's member functions are impressively unintuitive, and not all of them should be public. #89
• UI::Render() and Camera::Render() should skip foreground/background if it's (0, 0, 0, 0). Regarding simple textures, have a completely different loop for rendering. #90