sh/vim/tmux: Remove traces of base16

Base16 is a very interesting framework for themes, but it has a number
of limitations that make it suboptimal for use in editors, particularly
Vim.

Besides, the project has been trying to renew itself in the absence of
its original author — which is a good initiative — but it might take a
while before the new spec becomes stable.

A good summary:
tinted-theming/home#52 (comment)

.gitmodules

@@ -1,10 +1,3 @@
-[submodule "Vim Base16 color scheme"]
-	path = vim/pack/ui/start/base16-vim
-	url = https://github.com/base16-project/base16-vim.git
-	branch = main
-[submodule "Vim Base16 color schemes for Lightline"]
-	path = vim/pack/ui/start/base16-vim-lightline
-	url = https://github.com/mike-hearn/base16-vim-lightline.git
 [submodule "Vim Tabular plugin"]
 	path = vim/pack/format/start/tabular
 	url = https://github.com/godlygeek/tabular.git

tmux.conf

@@ -25,7 +25,3 @@ set -g renumber-windows on   # renumber windows when a window is closed
 set -g base-index 1          # start windows numbering at 1
 setw -g pane-base-index 1    # start pane numbering at 1
 set -sg escape-time 10       # shorten waiting time after Esc
-
-# base16 color theme
-# requires shell colors configured by https://github.com/chriskempson/base16-shell
-source-file ~/.tmux/tmux-base16.conf

vim/settings/lightline.vim

@@ -1,5 +1,4 @@
 let g:lightline = {
-      \ 'colorscheme': substitute(g:colors_name, '-', '_', 'g'),
       \ 'active': {
       \   'left'  : [ [ 'mode', 'paste' ], [ 'readonly', 'fugitive', 'filename', 'modified' ] ],
       \   'right' : [ [ 'lineinfo' ], [ 'percent' ], [ 'fileformat', 'fileencoding', 'filetype' ], [ 'go' ] ]

vimrc

@@ -75,18 +75,6 @@ if ($TERM_PROGRAM != 'Apple_Terminal')
   endif
 endif
 
-" Base16 color scheme
-if exists('$BASE16_THEME')
-  \ && (!exists('g:colors_name')
-  \ || g:colors_name != 'base16-$BASE16_THEME')
-
-  if ($TERM_PROGRAM == 'Apple_Terminal')
-    let base16colorspace=256    " take into account that the shell's colorspace was modified by base16-shell
-  endif
-
-  colorscheme base16-$BASE16_THEME
-endif
-
 " ============ Plugin customizations =============
 
 so ~/.vim/settings.vim

zsh/zimrc

@@ -18,9 +18,6 @@ zmodule termtitle
 # Utility aliases and functions. Adds colour to ls, grep and less.
 zmodule utility
 
-# Base16 shell colors
-zmodule base16-project/base16-shell
-
 #
 # Prompt
 #