The <tt> tag is deprecated, according to:
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/tt

The <code> tag is proposed as a replacement. It has the same intented
semantics: an inline block of code:
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/code

Closes #41.

Removed some visitor uses in mia, and moved some leftover mia templates from process to mia/. refs: #11

Signed-off-by: Mattia Rizzolo <mattia@debian.org>