Update URLs
.vimrc: Treat `.md` files as Markdown

`filetype` is set implicitly, without using setfiletype, because `*.md` is already associated with Modula-2 files and `setfiletype` doesn’t allow `filetype` to be set twice.

`setlocal` is used to apply a new `filetype` value for each Markdown file as it is being added to the buffer.

Fixes #418. Closes #419.
.functions: Add SNI support in `getcertnames`
Update URLs
.functions: Improve `getcertnames`
When updating calcentral, make sure to be on master
Merge remote-tracking branch 'mat/master'

* mat/master:
  .functions: Improve `getcertnames`
  Update URLs
  .functions: Add SNI support in `getcertnames`
  .vimrc: Treat `.md` files as Markdown
  Update URLs
Update CalCentral specific commands