[completion] Improve fuzzy completion matching

This will present the menu in case of ambiguous matches, and also expand
by any separator, not just `[._-]`.

Based on the configuration suggested at
https://superuser.com/a/815317/637926

Closes #212

modules/completion/init.zsh

@@ -56,7 +56,7 @@ zstyle ':completion:*:warnings' format '%F{red}-- no matches found --%f'
 zstyle ':completion:*' format '%F{yellow}-- %d --%f'
 zstyle ':completion:*' group-name ''
 zstyle ':completion:*' verbose yes
-zstyle ':completion:*' matcher-list 'm:{a-zA-Z}={A-Za-z}' 'r:|[._-]=* r:|=*' 'l:|=* r:|=*'
+zstyle ':completion:*' matcher-list 'r:|?=** m:{a-zA-Z}={A-Za-z}'
 
 # directories
 zstyle ':completion:*:default' list-colors ${(s.:.)LS_COLORS}