Shorten window title text

Modify Get-PromptPath to return full dir when path is equal to $Home.
It will use ~ when path is in a subdir *under* $HOME.

This does not address other path shortening techniques.
We could do those in this PR or another one.

Fixes #565

src/PoshGitTypes.ps1

@@ -271,7 +271,7 @@ class PoshGitPromptSettings {
     [string[]]$RepositoriesInWhichToDisableFileStatus = @()
 
     [string]$DescribeStyle = ''
-    [psobject]$WindowTitle = {param($GitStatus, [bool]$IsAdmin) "$(if ($IsAdmin) {'Administrator: '})$(if ($GitStatus) {"posh~git ~ $($GitStatus.RepoName) [$($GitStatus.Branch)] ~ "})PowerShell $($PSVersionTable.PSVersion) $([IntPtr]::Size * 8)-bit ($PID)"}
+    [psobject]$WindowTitle = {param($GitStatus, [bool]$IsAdmin) "$(if ($IsAdmin) {'Admin: '})$(if ($GitStatus) {"$($GitStatus.RepoName) [$($GitStatus.Branch)]"} else {Get-PromptPath}) - PowerShell $($PSVersionTable.PSVersion) $([IntPtr]::Size * 8)-bit ($PID)"}
 
     [PoshGitTextSpan]$DefaultPromptPrefix       = ''
     [PoshGitTextSpan]$DefaultPromptPath         = '$(Get-PromptPath)'

src/Utils.ps1

@@ -300,8 +300,10 @@ function Get-PromptPath {
 
     $stringComparison = Get-PathStringComparison
 
-    # Abbreviate path by replacing beginning of path with ~ *iff* the path is in the user's home dir
-    if ($abbrevHomeDir -and $currentPath -and $currentPath.StartsWith($Home, $stringComparison)) {
+    # Abbreviate path by replacing beginning of path with ~ *iff* the path is under the user's home dir
+    if ($abbrevHomeDir -and $currentPath -and !$currentPath.Equals($Home, $stringComparison) -and
+        $currentPath.StartsWith($Home, $stringComparison)) {
+
         $currentPath = "~" + $currentPath.SubString($Home.Length)
     }