Failing tests with Undo backend

[gareth-rees]

• TestRestartRewindAfterEnd
• TestRerecord
• TestCallFunction case fn2clos(12)
• TestCallFunction case pa2 = getAStructPtr(8); pa2
• TestCallFunction case str = "a new string"; str

[mark-undoio]

TestCallFunction for fn2clos(12) fails because it requires state persist in the replay process from the previous call to fn2close(11) - that's just not how calls work with the Undo Engine, so this isn't concerning in tself.

[mark-undoio]

TestCallFunction for pa2 = getAStructPtr(8); pa2 fails because it relies on on state persisting across statements within the call command. Right now it doesn't - we clear up the state as soon as the function call has completed.

We could change this with the right changes in Delve.

[mark-undoio]

TestCallFunction for str = "a new string"; str looks like the same issue as for pa2 - we don't persist state changes for the whole call command. We could do this if we wanted.

[mark-undoio]

TestRestartRewindAfterEnd and TestRerecord both pass now.