MEGA65: allow pre-init Attic RAM content

Allow Attic RAM to be pre-inited from the content of a file, given by
the CLI option "-initattic FILENAME".

Idea from @ki-bo on Discord

Also can be part of #238 ... though that issue has bigger scope.

targets/mega65/configdb.c

@@ -73,6 +73,7 @@ static const struct xemutools_configdef_str_st str_options[] = {
 	{ "importbas",	NULL, "Import and RUN BASIC65 program from TEXT file", &configdb.importbas },
 	{ "cartbin8000",NULL, "Load binary cartridge image from $8000", &configdb.cartbin8000 },
 	{ "winpos",	NULL, "Window position: x,y (integers)", &configdb.winpos },
+	{ "initattic",	NULL, "Pre-fill the Attic RAM with the content of a file", &configdb.init_attic },
 	{ NULL }
 };
 
@@ -153,7 +154,7 @@ static const void *do_not_save_opts[] = {
 	&configdb.matrixstart,
 	&configdb.dumpmem, &configdb.dumpscreen, &configdb.screenshot_and_exit,
 	&configdb.testing, &configdb.hyperdebug, &configdb.hyperdebugfreezer, &configdb.usestubrom, &configdb.useinitrom, &configdb.useutilmenu,
-	&configdb.cartbin8000, &configdb.winpos, &configdb.ramcheckread,
+	&configdb.cartbin8000, &configdb.winpos, &configdb.ramcheckread, &configdb.init_attic,
 	NULL
 };
 

targets/mega65/configdb.h

@@ -113,6 +113,7 @@ struct configdb_st {
 	int	matrixdisable;
 	char	*winpos;
 	int	ramcheckread;
+	char	*init_attic;
 };
 
 extern struct configdb_st configdb;

targets/mega65/mega65.c

@@ -376,6 +376,8 @@ static void mega65_init ( void )
 	}
 	// Fill memory with the needed pre-initialized regions to be able to start.
 	preinit_memory_for_start();
+	if (configdb.init_attic)
+		xemu_load_file(configdb.init_attic, attic_ram, 1, 8 << 20, "Cannot initialize Attic RAM from a file");
 	// *** Image file for SDCARD support, and other related init functions handled there as well (eg d81access, fdc init ... related registers, etc)
 	if (sdcard_init(configdb.sdimg,
 #ifndef		XEMU_ARCH_HTML