fix defcustom for org2blog/wp-track-posts

be3c8f9b changed this variable from a single string to a list of two
strings, where the second value is the headline to store log entries
under.

Also it appears that the code no longer works if the first value is nil.
Get tests passing!

- unnumbered changes caused html export to change.
- LaTeX export output also changed for equations.
Add build status to README.
Retrieve name of medium image thumbnail via xmlrpc

As the first step in supporting the use of automatically generated
Wordpress thumbnails (org2blog issue #158), use WordPress XMLRPC
to retrieve media information, including names of automatically created
thumbnail images.
Read from three-part image cache string
Replace <img> tag with href and img thumbnail
Image thumbnail behaviour now optional

Image thumbnail behaviour can now be configured using
org2blog/wp-image-thumbnails, which is by default off.
fix :syntaxhl by supporting #+ATTR_WP: :syntaxhl (#169)

Based on a conversation on #emacs with ngz and punchagan, it became
clear that the previous code didn't work.  Thanks to ngz for the
suggestion on a way forward.

Fixes #169.
Whitespace fixes.
Add test for sourcecode shortblock attributes.
remove org2blog/wp-sourcecode-langs

org2blog/wp-sourcecode-langs duplicates a list of supported languages
which depends entirely on the version of the WordPress SyntaxHighlighter
being used, so it is impossible to maintain this list to be correct for
all users, and it is unrealistic to expect users to maintain it to be
accurate.

Additionally, the only effect the variable has is to force the shortcode
to be "text" in case an language is chosen which is not in this list.
In that case, forcing it to text is almost certainly not what the user
would want or expect.

Therefore it is better to adhere to the DRY rule and just eliminate this
duplication.
Get tests passing after removal of lang-list.
Fix access to org2blog/wp-shortcode-langs-map.

- org2blog/wp-shortcode-langs-map is defined as an alist not a plist.

Conflicts:
	ox-wp.el
Add a test for langs map.
We don't unset anything, so we don't need to reset.
Merge pull request #166 from aspiers/fix/wp-track-posts-type

fix defcustom for org2blog/wp-track-posts
Don't eval username and password.

Users should instead set blog details with ` and , if required.

Changed while trying to debug #162.  This does not fix the issue,
though.
Change example blocks to source blocks in README.

[skip ci]
Recommend using auth-source instead of netrc.

[skip ci]  #162
Inserting newline sometimes indents

This breaks looking for already uploaded images.