Replace push with add-to-list in layer init functions and related code.
Modify spacemacs|add-toggle to check for and update an existing toggle in
spacemacs-toggles and only create a new toggle if none already existed.
Replace a conditional push onto erc-packages with use of :toggle.
When initializing which-key, set which-key-replacement-alist to its default
or customized setting before adding all the Spacemacs replacements. We
want to keep the stock replacements but avoid adding duplicates of the
Spacemacs replacements.
Replace the emacs-lisp-mode-hook lambda with a named function to avoid
adding duplicate hooks (which can add duplicate definitions of the
evil-surround pair).
Delete the quote preceding the lambda in spacemacs|add-toggle to avoid
the following warning:
.emacs.d/core/core-toggle.el: (lambda (x) ...) quoted with ' rather than with #'
While #' would be more correct than ', there is no need to quote the
lambda at all.
Modify macro spacemacs|add-toggle to create additional sets of functions for
each supported modes when the toggle is major mode specific.
A toggle is major mode specific when it is bound to keys using the keyword
:evil-leader-for-mode
Updare documentation to add a section on toggles in the Spacemacs concepts.
This commit introduces two new options to add-toggle:
:prefix, a symbol that is bound to the raw prefix argument (as
in `(interactive "P") forms).
:on-message, an expression overriding the default 'on' toggle
message (useful to document a toggle's argument).
These new options are applied to long-lines' toggle, so we can choose
how many lines to toggle it on via a raw prefix argument.
