Use .vimrc instead of .exrc. Also fix .ashrc.

I have the entire Alpine Linux repository mirrored. I might as well use
the fancy vi implementation. Syntax highlighting is kinda nice.

.ashrc

@@ -1,5 +1,7 @@
 # If not running interactively, don't do anything
-[[ $- != *i* ]] && return
+if ! echo $- | grep 'i' > /dev/null; then
+	return
+fi
 
 is_ssh() {
 	if [ -n "$SSH_CLIENT" ] || [ -n "$SSH_CONNECTION" ] || [ -n "$SSH_TTY" ]; then

.exrc

@@ -1,8 +0,0 @@
-set autoindent
-set number
-set ruler
-set tabstop=4
-set shiftwidth=4
-set showmatch
-set exrc
-set colorcolumn=72,80

.vimrc

@@ -0,0 +1,15 @@
+" Supported by almost all vi implementations.
+set autoindent
+set number
+set ruler
+set tabstop=4
+set shiftwidth=4
+set expandtab
+set showmatch
+set exrc
+
+" Supported only by vim. If running a non-vim vi, remove all comments
+" and everything below this line.
+set syntax=on
+set colorcolumn=72,80,100
+