Add help and FontName parameter.

This commit allows the user to specify a subset of fonts to install e.g. ./install.ps1 fura-*,hack-* will install all the FuraMono and Hack fonts. Support for the -WhatIf parameter was also added so you can see what fonts would be installed (without actually installing the fonts).

install.ps1

@@ -1,3 +1,41 @@
-$sa = new-object -comobject shell.application
-$fonts =  $sa.NameSpace(0x14)
-gci $PSScriptRoot -i *.ttf, *.otf -Recurse | %{$fonts.CopyHere($_.FullName)}
+<#
+.SYNOPSIS
+    Installs the provided fonts.
+.DESCRIPTION
+    Installs all the provided fonts by default.  The FontName
+    parameter can be used to pick a subset of fonts to install.
+.EXAMPLE
+    C:\PS> ./install.ps1
+    Installs all the fonts located in the Git repository.
+.EXAMPLE
+    C:\PS> ./install.ps1 furamono-, hack-*
+    Installs all the FuraMono and Hack fonts.
+.EXAMPLE
+    C:\PS> ./install.ps1 d* -WhatIf
+    Shows which fonts would be installed without actually installing the fonts.
+    Remove the "-WhatIf" to install the fonts.
+#>
+[CmdletBinding(SupportsShouldProcess)]
+param(
+    # Specifies the font name to install.  Default value will install all fonts.
+    [Parameter(Position=0)]
+    [string[]]
+    $FontName = '*'
+)
+
+$fontFiles = New-Object 'System.Collections.Generic.List[System.IO.FileInfo]'
+foreach ($aFontName in $FontName) {
+    Get-ChildItem $PSScriptRoot -Filter "${aFontName}.ttf" -Recurse | Foreach-Object {$fontFiles.Add($_)}
+    Get-ChildItem $PSScriptRoot -Filter "${aFontName}.otf" -Recurse | Foreach-Object {$fontFiles.Add($_)}
+}
+
+$fonts = $null
+foreach ($fontFile in $fontFiles) {
+    if ($PSCmdlet.ShouldProcess($fontFile.Name, "Install Font")) {
+        if (!$fonts) {
+            $shellApp = New-Object -ComObject shell.application
+            $fonts = $shellApp.NameSpace(0x14)
+        }
+        $fonts.CopyHere($fontFile.FullName)
+    }
+}