Add module for writeroom-mode

It has issues with linum-mode, so currently linum-mode needs to be
manually disabled. I will make it automatically toggle linum-mode when
enabling/disabling writeroom-room at some point.

core/siren-modules.el

@@ -122,6 +122,9 @@
 (require 'siren-ox-gfm)
 (require 'siren-ox-jira)
 
+;; Writing
+(require 'siren-writeroom)
+
 ;; Languages
 (require 'siren-coffee)
 (require 'siren-conf)

modules/writing/siren-writeroom.el

@@ -0,0 +1,26 @@
+;;; siren-writeroom.el --- jimeh's Emacs Siren: writeroom-mode configuration.
+
+;;; Commentary:
+
+;; Basic configuration for writeroom-mode.
+
+;;; Code:
+
+(use-package writeroom-mode
+  :commands
+  writeroom-mode
+  global-writeroom-mode
+
+  :bind
+  (:map writeroom-mode-map
+        ("C-M-<" . writeroom-decrease-width)
+        ("C-M->" . writeroom-increase-width)
+        ("C-M-=" . writeroom-adjust-width))
+
+  :config
+  (setq writeroom-global-effects nil
+        writeroom-restore-window-config t
+        writeroom-width 82))
+
+(provide 'siren-writeroom)
+;;; siren-writeroom.el ends here