This patch also removes the (unused) "compile" subcommand and replaces
it with a flag "-c" / "--compile" which prints the output in formatted
to the terminal.
Compiling the output from markdown to HTML and showing in the browser is
not yet possible.
The imag-view command was redesigned with this change. It now looks up
view-templates in the config and calls them with the "in" subcommand.
This way, an entry can be viewed with editor, browser or whatever one
likes.
Compiling markdown is not supported yet.
