Return fontenc to packages present in beamer

luximono needs it
First attempt
Source code blocks transcoding works
Exporting function useful for testing
Inline latex fragment transcoding works
Display math is exported now
Bars | changed to \vert in inline math mode.
Template function in kramdown

Replacement filters are to be included here
Removed stuff from rvf-org.el already covered
Support more image extensions
Publishing function
Fix some white space
Use new kramdown exporter
Set publishable graphic extensions
Merge branch 'kramdown' into devel