Re: [clipboard-apis] Non Recognizable formats (#9)

@hallvors 
Regarding file vs. string. A data transfer item has a "kind" of either "string" or "file". There needs to be some way of specifying which kind will be returned by a paste operation. Additionally, the encoding of strings would also need to be specified. The way I solved this in the chrome extension I made to demonstrate proof of concept (currently only working on windows) is to specify the encoding on a per osHandle basis so the syntax is:
```javascript
registerClipboardFormat(String mimeType, Object osHandles);
```
where osHandles is a dictionary that uses the os specific handle names as keys and then an encoding enum as values where the encodings currently supported are:

`ASCII`, `UTF_8`, `UFT_16`, and `BINARY`

The binary encoding always returns files, while the other three return strings (in standard UTF-16 JS strings. The encoding us just for how the string is stored on the OS clipboard)

So for my Mathcad usage I called:
```javascript
registerClipboardFormat("application/vnd.mathsoft.equation+xml",{
    "XMCD Format":registerClipboardFormat.formats.UTF_16,
    "com.mathsoft.xml":registerClipboardFormat.formats.UTF_16
});
```

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/clipboard-apis/issues/9#issuecomment-124121821