Org reader: Add support for figures

Support for figures (images with name and caption) is added.
Org writer: Fix output for linebreaks

Hard linebreaks in Org mode are represented by the string "\\" as the
last characters in a line.  Adds this feature to the Org-mode writer.
Org reader: Read linebreaks

Linebreaks are marked by the string `\\` at the end of a line.
Fix editorconfig for test files

Test output files should be exactly as defined with regard to trailing
whitespace.  This keeps editorconfig from breaking those files.
Org reader: Removed ANN pragma.

This relies on Template Haskell, which causes problems in Windows
due to libraries with C dependencies.  We need to avoid using TH
in pandoc code.
Merge pull request #1238 from tarleb/org-figures

Org reader: Add support for figures
Merge pull request #1239 from tarleb/org-linebreak

Org linebreaks
Merge pull request #1240 from neilmayhew/master

Docbook output of Line Blocks