Video features and fixes:

Added the Mach8 and Mach32 ISA/VLB/PCI cards (initial implementation and MCA coming soon for the Mach32) and their corresponding EEPROM's.
Added INMOS XGA ISA card and updated the SVGA core to reflect its mapping as well as the Mach8/32 mapping when in 8514 monitor mode.
Mark the XGA button as already checked and locked when a standalone XGA BIOS card is present like the INMOS one. (QT only)
Same concept as above, but applies to the Mach8 and 32 for the 8514 option as well. (QT only)

src/include/86box/vid_xga.h

@@ -36,6 +36,7 @@ typedef struct xga_t {
     mem_mapping_t  linear_mapping;
     mem_mapping_t  video_mapping;
     rom_t          bios_rom;
+    rom_t		   vga_bios_rom;
     xga_hwcursor_t hwcursor, hwcursor_latch;
     PALETTE        extpal;
 
@@ -57,7 +58,7 @@ typedef struct xga_t {
     uint8_t  clk_sel_1, clk_sel_2;
     uint8_t  hwc_control;
     uint8_t  bus_arb;
-    uint8_t  select_pos_isa;
+    uint8_t  isa_pos_enable;
     uint8_t  hwcursor_oddeven;
     uint8_t  cfg_reg_instance;
     uint8_t  rowcount;
@@ -70,6 +71,8 @@ typedef struct xga_t {
     uint8_t  sprite_data[1024];
     uint8_t  scrollcache;
     uint8_t  direct_color;
+    uint8_t  dma_channel;
+    uint8_t  instance_isa, instance_num, ext_mem_addr;
     uint8_t *vram, *changedvram;
 
     int16_t hwc_pos_x;