git related improvements and implementations

+ Get-GitRepo - Clone or update a repo, with tag support
+ Get-GitHubReleaseTag - Grab tag from latest release page
+ Refresh-GitRepo - Stage all possible changes, discarding any
previously stageds changes
= GitHub repo is now git repo - as some code isn't GitHub specific
+ cat Alias for Get-Content
= Get-PossiblArguments improvement
= Invoke-WebDownload fix
= dcedit fixing bad argument processing

git/Get-GitRepo.ps1

@@ -0,0 +1,29 @@
+[CmdletBinding(SupportsShouldProcess)]param(
+    [Parameter(Mandatory)]
+    [string]$LocalPath,
+    [Parameter(Mandatory)]
+    [string]$GitOrigin,
+    [string]$Branch='HEAD'
+)
+$local:gitPath = Join-Path 'themes' 'plextheme' | Get-Path
+function doGit { git "--git-dir=`"$(Join-Path $LocalPath '.git')`"" "--work-tree=`"$LocalPath`"" $args }
+$local:savedErrorActionPreference = $ErrorActionPreference
+$ErrorActionPreference = 'Stop'
+$local:exists = Test-Path $LocalPath
+try {
+    if( $exists ) {
+        # Update code from git repo
+        Write-Verbose "Pulling from [$GitOrigin] into [$LocalPath] on branch/tag '$Branch'..."
+        doGit fetch --quiet
+    } else {
+        git clone $GitOrigin $LocalPath
+    }
+    doGit checkout $Branch --quiet
+    if( $exists ) {
+        doGit status
+    }
+} catch {
+    throw $_
+} finally {
+    $ErrorActionPreference = $savedErrorActionPreference
+}