unicode: fix case-mapping for roman numerals!!
Hurray!
Also fix the mystical U+0345 COMBINING GREEK YPOGEGRAMMENI,
so everyone is satisfied.
Also add a -local flag to use local files for faster turnaround
when debugging.

R=rsc
CC=golang-dev
https://golang.org/cl/4825054
diff --git a/src/pkg/unicode/letter_test.go b/src/pkg/unicode/letter_test.go
index c4e26df..8d2665a 100644
--- a/src/pkg/unicode/letter_test.go
+++ b/src/pkg/unicode/letter_test.go
@@ -212,6 +212,10 @@
 	{UpperCase, 0x10450, 0x10450},
 	{LowerCase, 0x10450, 0x10450},
 	{TitleCase, 0x10450, 0x10450},
+
+	// Non-letters with case.
+	{LowerCase, 0x2161, 0x2171},
+	{UpperCase, 0x0345, 0x0399},
 }
 
 func TestIsLetter(t *testing.T) {