Added the function 'Update-FirstObjectProperties'

Added help text in 'Export-Excel'
Added try/catch to 'Install' and 'InstallModule'
Improved code readability in 'Install' and 'InstallModule'

Install.ps1

@@ -1,52 +1,94 @@
-param([string]$InstallDirectory)
+<# 
+    .SYNOPSIS   
+        Download the module files from GitHub.
 
-$fileList = echo `
-    EPPlus.dll `
-    ImportExcel.psd1 `
-    ImportExcel.psm1 `
-    Export-Excel.ps1 `
-    New-ConditionalFormattingIconSet.ps1 `
-    Export-ExcelSheet.ps1 `
-    New-ExcelChart.ps1 `
-    Invoke-Sum.ps1 `
-    InferData.ps1 `
-    Get-ExcelColumnName.ps1 `
-    Get-XYRange.ps1 `
-    Charting.ps1 `
-    New-PSItem.ps1 `
-    Pivot.ps1 `
-    New-ConditionalText.ps1 `
-    Get-HtmlTable.ps1 `
-    Import-Html.ps1 `
-    Get-ExcelSheetInfo.ps1 `
-    Get-ExcelWorkbookInfo.ps1 `
-    Get-Range.ps1 `
-    TrackingUtils.ps1 `
-    Copy-ExcelWorkSheet.ps1 `
-    Set-CellStyle.ps1 `
-    plot.ps1
+    .DESCRIPTION
+        Download the module files from GitHub to the local client in the module folder.
+#>
 
-if ('' -eq $InstallDirectory)
-{
-    $personalModules = Join-Path -Path ([Environment]::GetFolderPath('MyDocuments')) -ChildPath WindowsPowerShell\Modules
+[CmdLetBinding()]
+Param (
+    [ValidateNotNullOrEmpty()]
+    [String]$ModuleName = 'ImportExcel',
+    [String]$InstallDirectory,
+    [ValidateNotNullOrEmpty()]
+    [String]$GitPath = 'https://raw.github.com/dfinke/ImportExcel/master'
+)
 
-    if (($env:PSModulePath -split ';') -notcontains $personalModules) {
-        Write-Warning "$personalModules is not in `$env:PSModulePath"
+Begin {
+    Try {
+        Write-Verbose "$ModuleName module installation started"
+
+        $Files = @(
+            'Charting.ps1',
+            'ConvertFromExcelData.ps1',
+            'ConvertFromExcelToSQLInsert.ps1',
+            'ConvertToExcelXlsx.ps1',
+            'Copy-ExcelWorkSheet.ps1',
+            'EPPlus.dll',
+            'Export-Excel.ps1',
+            'Export-ExcelSheet.ps1',
+            'Get-ExcelColumnName.ps1',
+            'Get-ExcelSheetInfo.ps1',
+            'Get-ExcelWorkbookInfo.ps1',
+            'Get-HtmlTable.ps1',
+            'Get-Range.ps1',
+            'Get-XYRange.ps1',
+            'Import-Html.ps1',
+            'ImportExcel.psd1',
+            'ImportExcel.psm1',
+            'InferData.ps1',
+            'Invoke-Sum.ps1',
+            'New-ConditionalFormattingIconSet.ps1',
+            'New-ConditionalText.ps1',
+            'New-ExcelChart.ps1',
+            'New-PSItem.ps1',
+            'Pivot.ps1',
+            'Plot.ps1',
+            'Set-CellStyle.ps1',
+            'TrackingUtils.ps1',
+            'Update-FirstObjectProperties.ps1'
+        )
     }
-
-    if (!(Test-Path $personalModules)) {
-        Write-Error "$personalModules does not exist"
+    Catch {
+        throw "Failed installing the module in the install directory '$InstallDirectory': $_"
     }
-
-    $InstallDirectory = Join-Path -Path $personalModules -ChildPath ImportExcel
 }
 
-if (!(Test-Path $InstallDirectory)) {
-    $null = mkdir $InstallDirectory
-}
+Process {
+    Try {
+        if (-not $InstallDirectory) {
+            Write-Verbose "$ModuleName no installation directory provided"
 
-$wc = New-Object System.Net.WebClient
-$fileList |
-    ForEach-Object {
-        $wc.DownloadFile("https://raw.github.com/dfinke/ImportExcel/master/$_","$installDirectory\$_")
+            $PersonalModules = Join-Path -Path ([Environment]::GetFolderPath('MyDocuments')) -ChildPath WindowsPowerShell\Modules
+
+            if (($env:PSModulePath -split ';') -notcontains $PersonalModules) {
+                Write-Warning "$ModuleName personal module path '$PersonalModules' not found in '`$env:PSModulePath'"
+            }
+
+            if (-not (Test-Path $PersonalModules)) {
+                Write-Error "$ModuleName path '$PersonalModules' does not exist"
+            }
+
+            $InstallDirectory = Join-Path -Path $PersonalModules -ChildPath $ModuleName
+            Write-Verbose "$ModuleName default installation directory is '$InstallDirectory'"
+        }
+
+        if (-not (Test-Path $InstallDirectory)) {
+            New-Item -Path $InstallDirectory -ItemType Directory -EA Stop | Out-Null
+            Write-Verbose "$ModuleName created module folder '$InstallDirectory'"
+        }
+
+        $WebClient = New-Object System.Net.WebClient
+        
+        $Files | ForEach-Object {
+            $WebClient.DownloadFile("$GitPath/$_","$installDirectory\$_")
+            Write-Verbose "$ModuleName installed module file '$_'"
+        }
+
+        Write-Verbose "$ModuleName module installation successful"
     }
+    Catch {
+        throw "Failed installing the module in the install directory '$InstallDirectory': $_"
+    }
+}