Add functions to neutralize/restore feebleline

Feebleline is not the only package to use extensively the echo area.
visual-regexp also does and have conflicts with feebleline.

Theses functions, deactivate feebleline without altering the mode state.
They can patch conflicts used in hooks like :

       (add-hook 'vr/initialize-hook #'initialize-without-feebleline)
       (add-hook 'vr/end-hook #'end-with-feebleline)

See benma/visual-regexp.el#60

feebleline.el

@@ -100,6 +100,12 @@
 (defvar feebleline--mode-line-format-previous)
 (defvar feebleline-last-error-shown nil)
 
+(defvar pils--feebleline-transient nil
+  "Store the transient state of `feebleline-mode',
+Used by `initialize-without-feebleline' and `end-with-feebleline',
+which can temporarly neutralize feebleline so another function may
+take control of the echo area.")
+
 (defface feebleline-git-face '((t :foreground "#444444"))
   "Example face for git branch."
   :group 'feebleline)
@@ -154,6 +160,24 @@
   "Macro for adding B to the feebleline mode-line, at the beginning."
   `(add-to-list 'feebleline-msg-functions ,@b nil (lambda (x y) nil)))
 
+(defun initialize-without-feebleline ()
+  "Neutralise `feebleline-mode', meant to be used in a hook,
+ before a conflictual command."
+  (when feebleline-mode
+    (setq feebleline-transient-state t)
+    (cancel-timer feebleline--msg-timer)
+    (remove-hook 'focus-in-hook 'feebleline--insert-ignore-errors)))
+
+(defun end-with-feebleline ()
+  "Restore `feebleline-mode', meant to be used in a hook,
+after a conflictual command."
+  (when feebleline-mode
+    (setq feebleline-transient-state nil)
+    (setq feebleline--msg-timer
+          (run-with-timer 0 feebleline-timer-interval
+                          'feebleline--insert-ignore-errors))
+    (add-hook 'focus-in-hook 'feebleline--insert-ignore-errors)))
+
 ;; (feebleline-append-msg-function '((lambda () "end") :pre "//"))
 ;; (feebleline-append-msg-function '(magit-get-current-branch :post "<-- branch lolz"))
 ;; (feebleline-prepend-msg-function '((lambda () "-") :face hey-i-want-some-new-fae))