Fix EvalBlock in destination block executing destination instead of source

Fix range eval executing named output blocks

Add range support to :EvalBlock

Add unit test infrastructure and g:medieval_sync option

Make it work for win32 cmd

Fix bug with configurable fences

Allow option labels to be set on a per-filetype basis

Fix `E872 NFA regexp Too many '('`

Make s:fences const

Make source fence patterns configurable

Define user command and Plug mapping in plugin file

Escape dot character in start pattern

Support rmd filetype

Minor doc updates

Clarify value of "tangle" option