New test output file, checking all display-relevant stuff.

This is the test file I wish I'd had while I was rewriting the
text-drawing function this week :-) Better late than never.

testdata/display.txt

@@ -0,0 +1,14 @@
+Test of all features involved in do_text()
+==========================================
+
+Reverse video + red on yellow:       bing! 
+Yellow on red should look the same:  bong! 
+
+Basic attrs, combining chars, both widths: Bold blink underline [Λ̊][チ][text]
+Wide char should be off by 1 narrow char: Bold blink underline [Λ̊][チ][text]
+
+Double width, double height. Should be red top, magenta bottom, blue DW only:
+#3Bold blink underline [Λ̊][チ][text]
+#4Bold blink underline [Λ̊][チ][text]
+#6Bold blink underline [Λ̊][チ][text]
+