pandoc: allow to include other files

The following block will inlcude a second markdown file:

```{.include}
path/to/other/markdown/file.md
```

Move all used pandoc filters from the latex/ base directory into
a new pandoc/ directory.

1 files changed, 0 insertions, 20 deletions

diff --git a/latex/pandoc_center_img.lua b/latex/pandoc_center_img.lua
deleted file mode 100644
index 18782725..00000000
--- a/latex/pandoc_center_img.lua
+++ /dev/null
@@ -1,20 +0,0 @@
--- Based on:
--- https://pandoc.org/lua-filters.html#center-images-in-latex-and-html-output
--- Licensed under MIT License found at:
--- https://github.com/TomBener/pandoc-templates/blob/05aba224519d8a2b037108948bde0d820860b786/LICENSE
-
--- Filter images with this function if the target format is LaTeX.
-if FORMAT:match('beamer') then
-  function Image(elem)
-    -- Surround all images with the 'center' class with image-centering raw LaTeX.
-    if elem.classes[1] == "center" then
-      return {
-        pandoc.RawInline('latex', '\\hfill\\break{\\centering'),
-        elem,
-        pandoc.RawInline('latex', '\\par}')
-      }
-    else
-      return elem
-    end
-  end
-end