Issue #3869

`text/troff` is the standard approved by IANA. Also add some
non-standard MIME types.
https://bugs.freedesktop.org/show_bug.cgi?id=5072

See http://spec.commonmark.org/0.24/#list-items

Closes #3833

Issue #3862

Closes #3861

Closes #3864

Closes #3802

This allows findModeByName to work for edn and seems more consistent
with how JSON is handled.

Closes #3846.

Closes #3849

Closes #3853

Issue #3852

When hovering a line with multiple lint annotations, codeMirror will
now show all the attached markers instead of just the first one

Closes #3847

Closes #3846

 * Support nested block comments.
 * Improve number and operator parsing.
 * Improve string parsing.
 * Style brackets correctly.
 * Improve #-words.

Fixes #3842.

Closes #3840

It's already listed above as "MariaDB SQL".

Also add the ".mps" extension to the MUMPS mode.

Closes #3834

Issue #3821

Rather than hard-coding the bare XML mode.

Issue #3829

`serializeable` → `serializable`
Replace `an` with `a` 
Remove extra `command`