Check if this is what is causing memcheck to fail.

A large history record could noticeably increase the execution time of the concrete algorithm otherwise.

We should only create a history record if we're tracking it as we only discard it later.

Should parameter should be int not double.

The assertGreater function wasn't available in python 2.6

No need for a new method as there is already a workable option.

This also gives WorkspaceProperty a temp value if it it doesn't have one.

Otherwise LoadProcessNexus modifies the execution counter when it loads
histories from file and the parent algorithm gets the incorrect exec count.

As you should never need to set the exec count except in Algorithm, I've made
the method private and made Algorithm a friend class.

This changeset allows us to use enableHistoryRecordingForChild() to turn
off recording the history for a DataProcessorAlgorithm. This will be useful when
we have large algorithm histories.

These are consistent with the functionality that is available in WorkspaceHistory.

These classes should now capture the history of child algorithms.