Dracula Theme & Tmux

- Add window padding, dracula color scheme, and change background opacity to 0.85 in alacritty.yml
- Add vim dracula theme as a submodule
- Add tmux plugin manager as submodule
- Add tpm, tmux-sensible, and dracula to .tmux.conf
- Change vim theme to dracula

.gitmodules

@@ -0,0 +1,6 @@
+[submodule ".vim/pack/themes/start/dracula"]
+	path = .vim/pack/themes/start/dracula
+	url = https://github.com/dracula/vim.git
+[submodule ".tmux/plugins/tpm"]
+	path = .tmux/plugins/tpm
+	url = https://github.com/tmux-plugins/tpm