FR: choose document provider for filetype

[Frenzie]

• KOReader version: a394e64
• Device: all

Issue

The DocumentRegistry merely returns the first match, which is tailored to what we know to work well in most cases. For example, PdfDocument handles .zip and CreDocument handles .otherthings.zip.

koreader/frontend/document/documentregistry.lua

Lines 16 to 28 in 495accf

	--- Returns the registered document handler.
	-- @string file
	-- @treturn string provider, or nil
	function DocumentRegistry:getProvider(file)
	-- TODO: some implementation based on mime types?
	for _, provider in ipairs(self.providers) do
	local suffix = string.sub(file, -string.len(provider.extension) - 1)
	if string.lower(suffix) == "."..provider.extension then
	-- if extension == provider.extension then
	return provider.provider
	end
	end
	end

But for certain filetypes we might want to choose which engine to use. Like the zip mentioned above, or even for EPUB when we bump MuPDF to a more recent version.