Replace default cd alias with cd function

Define cd to work more like Unix/Linux:

* No path argument changes to the users home directory
* Passing "-" for the path argument changes to the previous directory

alias.ps1

@@ -1,4 +1,4 @@
-# Remove these aliases to PowerShell builtins which clobber the actaul exes.
-Remove-Item alias:curl
-Remove-Item alias:wget
-# TODO: Remove default abbriviation aliases
+# Remove builtin aliases
+Remove-Item Alias:curl
+Remove-Item Alias:wget
+Remove-Item Alias:cd

profile.ps1

@@ -11,4 +11,5 @@ $OutputEncoding = New-Object -typename System.Text.UTF8Encoding
 . $PSScriptRoot\alias.ps1
 . $PSScriptRoot\utils.ps1
 . $PSScriptRoot\layout.ps1
-# TODO: $PSScriptRoot\build.ps1
+# TODO: . $PSScriptRoot\build.ps1
+# TODO: . $PSScriptRoot\autoenv.ps1

utils.ps1

@@ -1,2 +1,16 @@
-# TODO: Define cd to work with zero args for home and - for last directory
+# Define cd to work more like Unix/Linux:
+# * No path argument changes to the users home directory
+# * Passing "-" for the path argument changes to the previous directory
+$Global:cdPreviousPath = Get-Location
+function cd {
+  Param ([string]$Path)
+  if ($Path -eq "") {
+    $Path = "~"
+  } elseif ($Path -eq "-") {
+    $Path = $cdPreviousPath
+  }
+  $Global:cdPreviousPath = Get-Location
+  Set-Location -Path $Path
+}
+
 # TODO: Define rm to work with -rf and multiple entries