Removed text-encoding for smaller implementation

[oliverfoster]

127

• Removed text-encoding as library is deprecated and includes support for a lot of code pages which aren't needed here (99.1KB)
• Added utf8 only implementation of TextEncoder and TextDecoder for IE and Edge (6.28KB)
• Made sure IE10+ support is listed in the code
• Updated readme to show how to support IE10+
• Updated attachment test
• Added notes referring to all associated APIs and sources

To test TextDecoder and TextEncoder in isolation in IE/Edge (or any browser), you can use the API like this:

var str = "this is a string";
console.log("original:", str);
var uintarray = new TextEncoder("utf8").encode(str)
console.log("Uint8Array:", uintarray );
var newStr = new TextDecoder("utf8").decode(uintarray);
console.log("processed:", newStr);

To run the attachments test in the browser, just load the test file test/testAttachments.html. The test is located in test/tests/test.attachments.js.

Readme updated.

This is dependent on the answer to #135

[oliverfoster]

thanks for testing @brian-learningpool

[vbhayden]

Will look at this today for a merge.

[oliverfoster]

@FlorianTolk this PR is still valid and good to merge into master.