Provide default encoding aliases

[benoit74]

The scraper would benefit a lot from having default encoding aliases already embedded. In many situations, we can be 99% sure of the proper encoding to use.

Defaults should be for now:

• u => utf-8
• unicode => utf-8
• 65001 => utf-8
• urf-8 => utf-8
• utf-f => utf-8
• utf-08 => utf-8
• utp-8 => utf-8
• windows-8859-1 => iso-8859-1
• ansi => windows-1252
• uft-8 => utf-8
• iso-utf-8 => utf-8
• iso88591 => iso-8859-1

All these bad encoding have been found in the wild, and it is always a bit hard to fail a scrape "just for that", there is no ambiguities in these cases.

Setting the encoding aliases CLI arg would not drop these defaults, but complement/enrich them. The CLI value must however superseed the default (i.e. if unicode is redefined in --encoding-aliases CLI argument, it is the value from CLI - and not the default - which is used).