Add "{To,From} EBCDIC" operations

This adds operations
+ "To EBCDIC"
+ "From EBCDIC"

This makes use of the npm codepage package but it is not installed as a
dependency.

Instead I used the `make.sh` script to export pages 37 and 500.

To my knowledge there is no way currently to only import individual code pages
from the npm package (hence the included script).

If we were to import the package directly it increases the build size by
2.7MB.

test/index.js

@@ -13,6 +13,7 @@ import "babel-polyfill";
 import TestRegister from "./TestRegister.js";
 import "./tests/operations/Base58.js";
 import "./tests/operations/ByteRepr.js";
+import "./tests/operations/CharEnc.js";
 import "./tests/operations/Compress.js";
 import "./tests/operations/FlowControl.js";
 import "./tests/operations/MorseCode.js";