-CGA, PCJr, Tandy: Add video blanking, change display start latch timing, sync pulse width correction,

-PCJr, Tandy: implement vertical retrace interrupt,
-PCJr, CGA: do line-by-line video emulation,
-PCJr: support on-screen change of color modes 4medium to 16low (used by Ghostbusters booter),
-All machines: only update the video timing when needed (Jungle Hunt, others that synchronize to the video screen might profit), only resize the output window when needed, start up the video more quickly at the beginning.

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3572

include/vga.h

@@ -111,6 +111,12 @@ typedef struct {
 	Bit32u full_enable_and_set_reset;
 } VGA_Config;
 
+typedef enum {
+	PART,
+	LINE,
+	//EGALINE
+} Drawmode;
+
 typedef struct {
 	bool resizing;
 	Bitu width;
@@ -144,6 +150,7 @@ typedef struct {
 		double hdend, htotal;
 		double parts;
 	} delay;
+	Bitu bpp;
 	double aspect_ratio;
 	bool double_scan;
 	bool doublewidth,doubleheight;
@@ -156,6 +163,7 @@ typedef struct {
 		Bit8u count,delay;
 		Bit8u enabled;
 	} cursor;
+	Drawmode mode;
 	bool vret_triggered;
 } VGA_Draw;
 
@@ -216,7 +224,7 @@ typedef struct {
 	Bit8u htotal;
 	Bit8u hdend;
 	Bit8u hsyncp;
-	Bit8u syncw;
+	Bit8u hsyncw;
 	Bit8u vtotal;
 	Bit8u vdend;
 	Bit8u vadjust;
@@ -372,8 +380,6 @@ typedef struct {
 
 typedef struct {
 	VGAModes mode;								/* The mode the vga system is in */
-	VGAModes lastmode;
-	Bits screenflip;
 	Bit8u misc_output;
 	VGA_Draw draw;
 	VGA_Config config;