Return errors when rendering
Detect missed index from front matter
Removing the use of slash

An oversight on my behalf.  The FromSlash method is used when writing
out the public file name.  There is one place where the slashes are
required which is setting the output file.  I replaced those instances
with filepath.Join which should do the right thing depending on the OS.
Formatting cleanup
Merge branch 'noahcampbell-index_reporting'