Enchantement: Add "Clear Ignored Words" button to Spellcheck dialog

[un_pogaz]

The Spellcheck dialog has a button for ignoring selected words, but it's not possible to clear the ignored words list from the dialog itself. If we want to reset the ignored words list we need to:

1. Close the Spellcheck dialog
2. Use the "Clear Ignored Words" action in the menu
3. Reopen the Spellcheck dialog

Adding a button "Clear Ignored Words" button into Spellcheck dialog would be more handy and made to have all the actions relative to spellcheck into the dialog.

[KevinH]

Using ignore all on a word temporarily adds it to the current dictionary in memory to make it quick to be ignored. But opening dictionaries and making them ready to use is time consuming. So resetting the ignored list is treated separately. You can of course save, close Sigil and reload your epub to achieve the same effect.

So we will not be adding that feature to the spellcheck dialog itself. Forced respelling is just too time consuming.

[un_pogaz]

So I tested and try different way like ignore a word into the code editor or ignore it from Spellcheck dialog, and/or clear the ignored words list, and in all case, the selected ignored words on the one had be symmetrical ignored on the second, and clear the ignored words list affect the both of them.

So the ignored words list is already shared between the code editor and the Spellcheck dialog, so I see no reason to dupicate the call behind the action "Tools>Spellcheck>Clear Ignored Words" into a button directly accessible from the dialog.

I don't know how you really want to implement it at the end, and I'm fine with that. Just, it's possible, it's really possible to add it, because everything is already here.
Except if I really miss a obscure step and memory interaction with the current implementation of the ignored words list and it cleaning action.