Added the following new machines:

- Olivetti M19.
- Olivetti M240.

Implemented mainboard jumper settings for Olivetti M24 machine:
- Like on a real M24, onboard video card can be disabled, and other video cards can be installed.
- Renamed m_olivetti_m24.c to m_xt_olivetti.c, as it handles all XT-class Olivetti machines.

Decoupled Olivetti OGC (640x400 extended CGA) from M24 machine code:
- OGC exists both as 16-bit proprietary card and 8-bit ISA card (GO708).
- Implemented underlined text handling in 80x25 character mode.
- Like Compaq CGA, replaced code portions common to CGA with calls to vid_cga.c.

src/win/Makefile.mingw

@@ -637,7 +637,7 @@ MCHOBJ		:= machine.o machine_table.o \
 		    m_xt_xi8088.o m_xt_zenith.o \
 		    m_pcjr.o \
 		    m_amstrad.o m_europc.o \
-		    m_olivetti_m24.o m_tandy.o \
+		    m_xt_olivetti.o m_tandy.o \
 		    m_at.o m_at_commodore.o \
 		    m_at_t3100e.o m_at_t3100e_vid.o \
 		    m_ps1.o m_ps1_hdc.o \
@@ -781,7 +781,8 @@ VIDOBJ		:= video.o \
 		    vid_voodoo_display.o vid_voodoo_fb.o \
 		    vid_voodoo_fifo.o vid_voodoo_reg.o \
 		    vid_voodoo_render.o vid_voodoo_setup.o \
-		    vid_voodoo_texture.o
+		    vid_voodoo_texture.o \
+			vid_ogc.o 
 
 PLATOBJ		:= win.o \
 		    win_dynld.o win_thread.o \