When IPropertyManager::getValue fails to assign the property to the
specified type, a runtime_error is raised. Changed the error messages in
all (specific) cases to specify exactly what type it was expecting,
i.e. (const) shared_ptr<X> not just X or const X.

IPropertyManager::getValue has specialisations for shared_ptr<T>and
const shared_ptr<T> for most types. The only missing ones were
IFunction, TableWorkspace and WorkspaceSingleValue, and these have been
added.

The previous code which derives from the old implementation of clone()
did not call the base class copy constructor but the base class
constructor. This seemed wrong (though I am not aware of any related
issues).

Added non-virtual clone() interface with a virtual private doClone()
method to Workspace and derived classes. Workspaces that had a clone()
method before were adapted to have a common interface everywhere. In
cases where there was no clone() method previously we simply throw an
error for now, until this new functionality is implemented.

Some tests/mocks had to be adapted since there there is a pure virtual
doClone() in all abstract classes.

Do to smart pointer incompatibilities (mainly due to old boost versions)
we had do extract the raw pointer from the unique_ptr returned by clone
and put it into a boost::shared_ptr manually, in some cases. See also
issue 12949.

Refs #9059

...from a success/failure boolean to a shared pointer to the new column.
Saves repeatedly having to go and fetch the column separately in an
algorithm I'm working on. Any existing places that check the return value
(there aren't many) will still work as the pointer will convert to bool.

I kept the return type of the exposed python method unchanged as the
Column class is not exposed to python and I didn't see any reason to do
so just for this.

instead of ITableWorkspace.h

refs #3641. First pass. It is known that the exact column list for the underlying tableworkspace is not confirmed.

mainly some changes to itableworkspace + column in connection with writing tables to nexus. re #2425