Rewritten parts of the 86F handler to minimize false CRC errors and misidentification of sectors;

Replaced IMG handler with one that now proxies to the 86F handler;
Applies the remaining Mainline PCem speedup commit;
Fixed the National Semiconductors PC87306 Super I/O Chip's serial port IRQ assignment;
DMF images are now loaded with the correct sector interleave, improving read/write speed;
XDF images are now loaded in a way that emulates the real order of the sectors on the track, improving read/write speed;
Added 16-bit physical memory read/write routines (mem_phys_readw, mem_phys_writew) and modified the 16-bit DMA code to use them instead of two 8-bit reads/writes.

src/Makefile.mingw

@@ -5,7 +5,7 @@ WINDRES = windres.exe
 CFLAGS = -O3 -march=native -mtune=native -fbranch-probabilities -fvpt -funroll-loops -fpeel-loops -ftracer -fomit-frame-pointer -ffast-math -msse -msse2 -msse3 -mssse3 -mfpmath=sse -mstackrealign
 OBJ = 386.o 386_dynarec.o 386_dynarec_ops.o 808x.o acer386sx.o acerm3a.o ali1429.o amstrad.o cdrom-ioctl.o cdrom-iso.o \
 	cdrom-null.o codegen.o codegen_ops.o codegen_timing_486.o codegen_timing_686.o codegen_timing_pentium.o codegen_timing_winchip.o codegen_x86.o compaq.o config.o cpu.o dac.o \
-	device.o disc.o disc_86f.o disc_fdi.o disc_img.o disc_random.o disc_sector_86box.o dma.o fdc.o fdc37c665.o fdc37c932fr.o fdd.o fdi2raw.o gameport.o headland.o i430hx.o i430lx.o i430fx.o \
+	device.o disc.o disc_86f.o disc_fdi.o disc_img_86box.o disc_random.o dma.o fdc.o fdc37c665.o fdc37c932fr.o fdd.o fdi2raw.o gameport.o headland.o i430hx.o i430lx.o i430fx.o \
 	i430nx.o i430vx.o i440fx.o ide.o intel.o intel_flash.o io.o jim.o joystick_ch_flightstick_pro.o joystick_standard.o joystick_sw_pad.o joystick_tm_fcs.o keyboard.o keyboard_amstrad.o keyboard_at.o \
 	keyboard_olim24.o keyboard_pcjr.o keyboard_xt.o lpt.o mcr.o mem.o memregs.o model.o mouse.o mouse_ps2.o \
 	mouse_serial.o ne2000.o neat.o nethandler.o nmi.o nvr.o olivetti_m24.o opti.o pc.o pc87306.o pci.o pic.o piix.o pit.o ppi.o ps1.o rom.o rtc.o \