try creating a nightly push to nuget script v1

this is intended to create nightly build with package
versions of the form x.y.z-yyyyMMdd.sha and
push them to nuget automatically, only where there
are new changes per day. since devops is a nightmare
and entirely untestable we will have to go through 20
iterations to actually get this to work

tools/get-main-version.ps1

@@ -0,0 +1,7 @@
+$xml = New-Object XML
+$xml.Load(".\tools\UglyToad.PdfPig.Package\UglyToad.PdfPig.Package.csproj")
+$current = $xml.Project.PropertyGroup[0].Version
+$hyphenIndex = $current.IndexOf('-')
+$len = If ($hyphenIndex -lt 0) { $current.Length } Else { $hyphenIndex }
+$version = $current.Substring(0, $len)
+Write-Output $version