Add new alignment running script 'gaudisplititer'

Currently, the infamous alignment 'gaudiiter.py' script does not lead to a converging alignment because the in-memory geometry updates are not propagated correctly. This is hopefully temporary, but it makes it not possible to run alignment in the master. The 'gaudipariter' script that would run iterations one job at a time no longer exists: it was deemed obsolete because it splits event processing over different processes, rather than different threads.

This branch introduces a new running script 'gaudisplititer' which behaves like the old 'gaudipariter' script: It runs each iteration as a separate process, writing and reading the constants via xml. Unlike gaudiiter, it gives a converging alignment in the master. It has a property to use multithreading using hive, but this is not entirely functional yet.

This branch also contains a bug fix: a function parameter of IAlignUpdateTool::process was passed by value rather than by reference.