Customizable reference link location

Same location options as with markdown-footnote-location: 'end, 'header,
or 'immediately.  Default is 'header.

In cases where the point is left after the newly link (when the URL is
given on the minibuffer prompt), print a message to indicate that the
definition was added, since it might not be visible from the link
location.

Includes basic unit tests.
Place definitions at end of 'block'

Now that block-movement functions exist, when location setting is
'immediately, use end of block rather than end of paragraph.  The
current definition of paragraph distinguishes, for example, individual
list items (regardless of whitespace) and hard line breaks.  The
definition of block does not.  Placing definitions at the end of the
block best matches what one intends with 'immediately, and what happened
when this was originally implemented.
Fix killing of footnotes from footnote text

Since footnote definitions look like reference definitions, consider
footnotes before reference definitions so that `markdown-footnote-kill'
is used to remove the marker as well.

Includes a unit test.
Likely markdown-mode 2.0 keybindings

Element insertion with C-c <char>, rather than double prefix.

Heading navigation with org-mode keybindings.
(This frees up sexp movement commands, which were overridden before.)
Dynamic loading and unloading for math support

Allow `markdown-enable-math' to be set as a local file variable, with
a predicate for ensuring it's safe.

Make `markdown-mode-font-lock-keywords' a local variable.

Add a font lock refresh function `markdown-reload-extensions', which
updates the font-lock keyword list for the current settings and
refontifies the buffer.

Rename regexes with -latex to more generic -math.

Includes unit tests for file local variables, dynamic loading, and
font lock.
Match headers before metadata blocks
Allow underscores and colons in equation labels
Add math.text test file