(API Change) libobs: Remove main window funcs/vars

(Non-compiling commit: windowless-context branch)

API Changed:
---------------------
Removed functions:
- obs_add_draw_callback
- obs_remove_draw_callback
- obs_resize
- obs_preview_set_enabled
- obs_preview_enabled

Removed member variables from struct obs_video_info:
- window_width
- window_height
- window

Summary:
---------------------
Changes the core libobs API to not be dependent upon a main window/view.
If you wish to draw to a window/view, use an obs_display object to
handle it.

This allows the use of libobs without requiring a window to be present
on the system.  This is also prunes code that had to be needlessly
duplicated to handle the "main" window.

libobs/obs.h

@@ -155,9 +155,6 @@ struct obs_video_info {
 	uint32_t            fps_num;       /**< Output FPS numerator */
 	uint32_t            fps_den;       /**< Output FPS denominator */
 
-	uint32_t            window_width;  /**< Window width */
-	uint32_t            window_height; /**< Window height */
-
 	uint32_t            base_width;    /**< Base compositing width */
 	uint32_t            base_height;   /**< Base compositing height */
 
@@ -168,8 +165,6 @@ struct obs_video_info {
 	/** Video adapter index to use (NOTE: avoid for optimus laptops) */
 	uint32_t            adapter;
 
-	struct gs_window    window;        /**< Window to render to */
-
 	/** Use shaders to convert to different color formats */
 	bool                gpu_conversion;
 
@@ -528,19 +523,6 @@ EXPORT signal_handler_t *obs_get_signal_handler(void);
 /** Returns the primary obs procedure handler */
 EXPORT proc_handler_t *obs_get_proc_handler(void);
 
-/** Adds a draw callback to the main render context */
-EXPORT void obs_add_draw_callback(
-		void (*draw)(void *param, uint32_t cx, uint32_t cy),
-		void *param);
-
-/** Removes a draw callback to the main render context */
-EXPORT void obs_remove_draw_callback(
-		void (*draw)(void *param, uint32_t cx, uint32_t cy),
-		void *param);
-
-/** Changes the size of the main view */
-EXPORT void obs_resize(uint32_t cx, uint32_t cy);
-
 /** Renders the main view */
 EXPORT void obs_render_main_view(void);
 
@@ -568,9 +550,6 @@ EXPORT void obs_load_sources(obs_data_array_t *array);
 /** Saves sources to a data array */
 EXPORT obs_data_array_t *obs_save_sources(void);
 
-EXPORT void obs_preview_set_enabled(bool enable);
-EXPORT bool obs_preview_enabled(void);
-
 
 /* ------------------------------------------------------------------------- */
 /* View context */