Add support for EPUB, CBZ, FB2 and (O)XPS extension to doc view

Add support for EPUB, CBZ, FB2 and (O)XPS extension to doc view

* doc/emacs/misc.texi (Document View): Add requirements for new
extensions (i.e. mutool).

* lisp/doc-view.el (doc-view): Additionally update preliminary comment
(doc-view-custom-set-epub-font-size): redraw image after setting
(doc-view-unoconv-program): Put code all on one line
(doc-view-doc-type): Update docstring.
(doc-view-kill-proc): Fix comment indentation
(doc-view-mode-p):
Add check for new extensions and alternative check for PDF
(doc-view-pdf/ps->png): Associate new extension with png converter
(doc-view-convert-current-doc): Handle new extensions like PDF's
(doc-view-set-doc-type): Set correct doc-type for new extensions.

* lisp/files.el (auto-mode-alist):
Associate new extension types with doc-view.