Reject dictionaries with incomplete entropy tables

Reject dictionaries with incomplete entropy tables

If a dictionary specifies that a symbol has probability zero in its
`matchLength`, `literalLength`, or `offset` FSE table, but the symbol
appears when compressing input, the compressor fails.

Ensure that dictionaries support all `matchLength`, and `literalLength`
codes.  They must also support all of the `offset` codes required to
represent every possible offset that can appear in the first block.