msi: Installing to the 64 bit folder does now work.

And hopefully the x86 installing still works. We will see when
migrating this back to vsd-3.x.

Unfortunately I had to do some more reformatting to make the XML
generating easier to read. The actual changes are:

+ Platform="$::platform"

+ <SetDirectory Id="APPLICATIONFOLDER"
+ Value="[$::pfilesfolder][ApplicationFolderName]"
+ >APPLICATIONFOLDER=""</SetDirectory>

+ <CustomAction Id="OverwriteWixSetDefaultPerMachineFolder"
+ Property="WixPerMachineFolder"
+ Value="[APPLICATIONFOLDER]"
+ Execute="immediate"
+ />

+ <Custom Action="OverwriteWixSetDefaultPerMachineFolder"
+ After="WixSetDefaultPerMachineFolder" />

• <Directory Id='ProgramFilesFolder' Name='PFiles'>

+ <Directory Id="$::pfilesfolder" Name='PFiles'>