Corrected a problem with an uninitialized entry in ExtCurStyle that

could cause serious errors on systems that do not auto-zero allocated
memory.  Also:  Fixed an error introduced by a recent commit to allocate
character memory for efReadLine() which frees the memory before reading
a .res.ext file, causing a crash when using "ext2spice" with the
"extresist on" option.

extract/ExtTech.c

@@ -810,8 +810,14 @@ ExtStyle *
 extTechStyleNew()
 {
     ExtStyle *style;
+    TileType r;
 
     style = extTechStyleAlloc();
+
+    /* This entry in ExtStyle is allocated and must be initialized */
+    for (r = 0; r < NT; r++)
+	style->exts_device[r] = NULL;
+
     extTechStyleInit(style);
     return style;
 }