Remove `basename` from core library

The features added by this function are not used anywhere.

Fix #151

lib/README.md

@@ -39,10 +39,6 @@ if available battery
 end
 ```
 
-#### `basename` _`<path> ...`_
-
-Wrap basename so it can handle multiple arguments.
-
 #### `refresh`
 
 Replace the running instance of fishshell with a new one causing Oh My Fish to reload as well.

lib/basename.fish

-# SYNOPSIS
-#   basename <string> [suffix]
-#   basename [-s suffix] <string> [string...]
-#
-# OVERVIEW
-#   variable arguments basename
-
-function basename -d "get the filename or directory part of a path"
-  if set -q argv[1]
-    set -l ext ""
-    switch $argv[1]
-      case -s
-        if test (count $argv) -gt 2
-          set ext $argv[2]
-          set argv $argv[3..-1]
-        else
-          echo "basename: Invalid number of arguments"
-          return 1
-        end
-    end
-    for path in $argv
-      command basename "$path" "$ext"
-    end
-  end
-end