GafferSeed
Merge pull request #1112 from appleseedhq/GafferSeedPR2

GafferSeed2
Fixed ObjectSource to work after create/undo/redo.

It was using an outdated way of using the result of an internal computation in the computation of another output - since DependencyNode::affects() is now (and has been for a long time) called for output plugs as well as inputs during dirty propagation there is not need for the additional intermediate plug.

Although this fix is good in that it tidies up some code, I suspect there's another problem somewhere which caused the input to the internal plug to be removed upon undo but not restored upon redo. This may need investigating in its own right at some point.

I have no idea why the unrelated SceneWriterTest was mucking about with the private __inputSource plug - it had no business being there.
Added appleseed to JH build config.
Removed unused includes from bindings.

This reveals that IECorePython::Wrapper is still in use in the bindings for `ParameterisedHolder`, `ApplicationRoot`, `Expression`, `Serialisation` and `ParameterHandler`. These are what we need to deal with for #1116.
Merge pull request #1114 from johnhaddon/objectSourceUndoRedoFix

Fixed ObjectSource to work after create/undo/redo.
Merge pull request #1117 from johnhaddon/removeIncludes

Removed unused includes from bindings.
Removed deprecated Path.addFilter() and Path.removeFilter() methods.
Added tokenize() function to StringAlgo.h.
Optimised PathMatcher with new tokenizer.

This approximately halves the time taken to construct a large PathMatcher from paths in string form.
Removed unused typedef from PathMatcher.
Removed relative imports from PathFilter classes.
WIP 1
Got filter signalling working.
Got copy() and info() working, with new attribute methods.
Got children() working.
Implemented remove() and __delitem__. FileSystemPathTest passes!
Added RunTimeTyped registrations for all python Path types.
Added binding for Path::emitPathChanged().

ScenePathTest passes!