[themes-megapack] Add `ewal-spacemacs-themes` to `themes-megapack` layer.

Currently, the theme also modifies `spacemacs-dark` if also loaded in
`dotspacemacs-themes`. A
[fix](https://github.com/nashamri/spacemacs-theme/pull/144) for this is on it's
way upstream to `spacemacs-theme`, but the maintainer already gave their
[blessing](https://github.com/nashamri/spacemacs-theme/issues/139).

CHANGELOG.develop

@@ -2586,6 +2586,7 @@ Other:
 - Remove themes that were deleted from Melpa (thanks to Henrique Jung)
 - Added =eziam-theme= and =kaolin-themes= (thanks to Sylvain Benner)
 - Added =doom-themes= (thanks to Codruț Constantin Gușoi)
+- Created and added =ewal-spacemacs-themes= (thanks to Uroš Perišić)
 **** Tmux
 - Prevent =tmux-command= at GUI mode (thanks to Isaac Zeng)
 - Fixed regression in tmux by setting keybindings using =use-package=

core/core-themes-support.el

@@ -196,6 +196,10 @@
     (doom-tron                        . doom-themes)
     (doom-vibrant                     . doom-themes)
     (doom-x                           . doom-themes)
+    (ewal-spacemacs-modern                . ewal-spacemacs-themes)
+    (ewal-spacemacs-modern-high-contrast  . ewal-spacemacs-themes)
+    (ewal-spacemacs-classic               . ewal-spacemacs-themes)
+    (ewal-spacemacs-classic-high-contrast . ewal-spacemacs-themes)
     (solarized-light                  . solarized-theme)
     (solarized-dark                   . solarized-theme)
     (spacemacs-light                  . spacemacs-theme)

layers/+themes/themes-megapack/README.org

@@ -13,6 +13,7 @@ This layer installs around 100 themes for Emacs.
 ** Features:
 - Have access to all included themes in this [[http://themegallery.robdor.com][theme gallery]] from [[http://www.twitter.com/robmerrell][Rob Merrell]].
 - Easily try a theme by invoking helm-themes with: ~SPC T s~.
+- Theme Spacemacs using [[https://github.com/dylanaraps/pywal][pywal]] by choosing one of the =ewal-spacemacs-*= themes.
 
 * Install
 To use this configuration layer, add it to your =~/.spacemacs=. You will need to

layers/+themes/themes-megapack/packages.el

@@ -36,6 +36,7 @@
     django-theme
     doom-themes
     dracula-theme
+    ewal-spacemacs-themes
     espresso-theme
     exotica-theme
     eziam-theme