Reimplement monitor capture

- Implement windows monitor capture (code is so much cleaner than in
   OBS1).  Will implement duplication capture later

 - Add GDI texture support to d3d11 graphics library

 - Fix precision issue with sleep timing, you have to call
   timeBeginPeriod otherwise windows sleep will be totally erratic.

plugins/win-capture/dc-capture.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#include <obs.h>
+
+#define NUM_TEXTURES 2
+
+struct dc_capture {
+	int        cur_tex;
+	texture_t  textures[NUM_TEXTURES];
+	bool       textures_written[NUM_TEXTURES];
+	int        x, y;
+	uint32_t   width;
+	uint32_t   height;
+	int        num_textures;
+
+	bool       compatibility;
+	HDC        hdc;
+	HBITMAP    bmp, old_bmp;
+	BYTE       *bits;
+
+	bool       capture_cursor;
+	bool       cursor_captured;
+	CURSORINFO ci;
+
+	bool       valid;
+};
+
+extern void dc_capture_init(struct dc_capture *capture, int x, int y,
+		uint32_t width, uint32_t height, bool cursor,
+		bool compatibility);
+extern void dc_capture_free(struct dc_capture *capture);
+
+extern void dc_capture_capture(struct dc_capture *capture, HWND window);
+extern void dc_capture_render(struct dc_capture *capture, effect_t effect);
+
+extern effect_t create_opaque_effect(void);