Remove pwd alias for currentdir

Name of the POSIX tool `pwd` is a shorthand for "print working
directory". Using it as an alias for `currentdir` is misleading, as
nothing is printed.

Furthermore, `pwd` is sometimes used as a shorthand for the password
database.

Author: tarleb

README.md

@@ -113,12 +113,6 @@ Returns:
 - A table of all entries in `directory` without the special entries (`.`
   and `..`).
 
-### pwd {#system-pwd}
-
-`pwd ()`
-
-An alias for [`currentdir`](#system-currentdir)
-
 ### setenv {#system-setenv}
 
 `setenv (var, value)`

src/Foreign/Lua/Module/System.hs

@@ -42,7 +42,6 @@ pushModule = do
   addFunction "env" env
   addFunction "getenv" getenv
   addFunction "ls" ls
-  addFunction "pwd" currentdir
   addFunction "setenv" setenv
   addFunction "tmpdirname" tmpdirname
   addFunction "with_tmpdir" with_tmpdir

test/system-module-tests.lua

@@ -37,9 +37,6 @@ assert(pcall(system.ls, 'README.md') == false)
 
 -- currentdir
 assert(type(system.currentdir()) == 'string')
--- pwd is an alias for currentdir
-assert(system.currentdir() == system.pwd())
-
 
 -- Complex scripts
 function in_tmpdir (callback)