internal/format: added symbol and number system data

This data is common to several number generation packages,
including currency and numbers.

Change-Id: I6af3cd92e4d2cc8adb8901f3b4edb6481902b9f7
Reviewed-on: https://go-review.googlesource.com/19196
Reviewed-by: Nigel Tao <nigeltao@golang.org>
7 files changed