* fixed target texture dimension when -intoverscan is used (this fixes the appereance of scanline and shadow mask)
* added target_scale and screen_count uniforms
* rounded corners now remain aligned with screen bounds when -intoverscan is used (single screen only)
* added simple procedural texture for vectors with rounded line ends and beam smoothness
* added optional -vector_beam_smooth option
* removed -antialias option, antialiasing is now always applied, except for plain D3D