Use DefaultForegroundColor for prompt text

The setting exists for legacy reasons: 02956e1.
It was removed in #202 and restored in #209 to avoid a breaking change.

Since we still have it, I suppose we might as well support using it to
control the prompt text color.

Author: dahlbyk

src/GitPrompt.ps1

@@ -128,6 +128,11 @@ if (Get-Module NuGet) {
 }
 
 function Write-Prompt($Object, $ForegroundColor = $null, $BackgroundColor = $null) {
+    $s = $global:GitPromptSettings
+    if ($s -and !$ForegroundColor) {
+        $ForegroundColor = $s.DefaultForegroundColor
+    }
+
     if ($BackgroundColor -is [string]) {
         $BackgroundColor = [ConsoleColor]$BackgroundColor
     }

src/posh-git.psm1

@@ -85,11 +85,11 @@ if ($ForcePoshGitPrompt -or !$currentPromptDef -or ($currentPromptDef -eq $defau
         $defaultPromptPrefix = [string]$GitPromptSettings.DefaultPromptPrefix
         if ($defaultPromptPrefix) {
             $expandedDefaultPromptPrefix = $ExecutionContext.SessionState.InvokeCommand.ExpandString($defaultPromptPrefix)
-            Write-Host $expandedDefaultPromptPrefix -NoNewline
+            Write-Prompt $expandedDefaultPromptPrefix
         }
 
         # Write the abbreviated current path
-        Write-Host $currentPath -NoNewline
+        Write-Prompt $currentPath -NoNewline
 
         # Write the Git status summary information
         Write-VcsStatus
@@ -110,7 +110,7 @@ if ($ForcePoshGitPrompt -or !$currentPromptDef -or ($currentPromptDef -eq $defau
         if ($GitPromptSettings.DefaultPromptEnableTiming) {
             $sw.Stop()
             $elapsed = $sw.ElapsedMilliseconds
-            Write-Host " ${elapsed}ms" -NoNewline
+            Write-Prompt " ${elapsed}ms" -NoNewline
         }
 
         $global:LASTEXITCODE = $origLastExitCode