Pier Cleanup

Previously, PRExportImportWidget was removed from Pier because it was replaced by a component, looking into removing PRSegmentPersistency - reasons are:

• The method cleanupPier won't work - PRKernel no longer has Instances
• There's no longer an ImageSegment for serialize: or Project for cleanupProcesses

Based on this mail chain, one possible replacement is using Fuel - PRFuelPersistency. The code can be found at:

  Gofer it
	squeaksource3: 'pierfuel';
	package: 'Pier-FuelPersistence-Core';
	package: 'Pier-FuelPersistence-Test';
	browseRemoteChanges.

Estimate how much work:

• PRFuelExporterImporter>>importNewKernelFromFilename: uses FileStream (as does #importNewKernelNamed:fromFilename:)
• PRFuelExporterImporter>>materializeKernelFrom: uses #isKindOf: for error checking, is this necessary?
• PRFuelPersistency's parent is PRDelayedPersistency, not PRImageSegment
• PRFuelPersistency>>importFromPathString:withPrefix: uses FSFilesystem
• What is the replacement for Smalltalk>>addToStartUpList:before:? See PRFuelPersistency>>initialize
• PRFuelPersistency>>materializationStream references MultiByteBinaryOrTextStream
• It seems unusual for 2012 code that this references DateAndTime instead of TimeStamp

There are some issues with PRReferenceStreamExporterImporter:

• ReferenceStream no longer exists
• This could be replaced by the code exporter, there are some issues:
  • Having too many users requires reducing literals
  • Page problems