This removes the various doom-line-number* variables and replaces it
with the Emacs 26 display-line-numbers API, which I've ported to Emacs
25.x (however, it uses nlinum under the hood, and not all of
display-line-numbers options are supported).
+ Make synosaurus unconditional
+ Move much of +write-mode into its hook
+ Conform README.org to template and expand it
+ Try to guess langtool-language-tool-jar
+ Update init.example.el entry
+ Remove redundant variables
+ Add +write-text-scale & +text-line-spacing variables
