Convert to SPDX license tags

This includes marking all documentation files CC-BY-SA-4.0.

python-capdl-tool: Handle set_mapping on frame cap

By default, the caps that get used to map frames into each component
are kept by the loader. However it is possible to describe in the spec a
mapped cap that gets moved into a target cspace. This allows components
to perform cache maintenance operations on the mapping or to unmap the
mapping if required. To make this mechanism easier to use, if a cap
passed into get_spec as an existing backing frame has had
set_mapping_deferred called on it, then the spec will call set_mapping
on the cap with the correct mapping container and slot. The loader will
then move the mapped cap into the cspace instead of copying it.

python-capdl-tool: Document Cap.set_mapping()

This function allows a mapped frame cap to be moved to a particular
cspace.

trivial: style changed files

python-capdl-tool: fix errors reported by pylint3

Fix errors reported by pylint3 --errors-only on .py files in
python-capdl-tool.

Revert "python-capdl-tool: check that cap rights aren't set on incorrect cap types"

This reverts commit 2cb3b36e73a84e4221677f7fb18294d0fabf1931.

python-capdl-tool: check that cap rights aren't set on incorrect cap types

python-capdl-tool: slightly clean up Cap initialisation and printing

Add new GrantReply right to capDL tools

python-capdl: Refactor Cap __init__ to take kwargs

Caps can have more attributes than read, write, grant and should be
supported via construction also.

Update IOPort model

Changes the model of the IOPorts in the capdl specification and the surrounding tools
to reflect a change in the kernel model. There is now a single IO port control capability
that can produce non overlapping IO port caps. Due to the non overlapping requirement the
capdl model treats the 'object' as an IO port cap issued from the control capability and
this is then duplicated at the cap level to produce all cap references.

Fix licenses

Support loading sched_control caps.

This change allows sched_control caps to be placed into CNodes and
updates the capdl-loader-app to copy them.

python-capdl: Define x86_64 types

[python-capdl-tool] Added mapping information to frame caps

python-capdl: Enable Python 3 compatibility settings from `__future__`.

This change enables a variety of Python 3 compatibility settings from
`__future__` when running Python 2. Essentially this forces all existing code
under Python 2 to conform to the Python 3 semantics. This makes bilingual
compatibility easier.

python-capdl: Make all intra-package imports relative.

This progresses compatibility with Python 3 to the point where this package can
be imported. I haven't explored further, but I believe the package still cannot
be used correctly under Python 3. More changes to come.

python-capdl: Change some `filter` calls to list comprehensions.

This commit converts two calls to `filter` into the corresponding list
comprehension. The motivation for this is movement towards Python 3
compatibility. In Python 3, `filter` returns a generator, not a list and so a
result that is expected to be iterated over multiple times does not function as
expected. There are many more changes needed for full Python 3 compatibility.
Python 2 functionality should be unaffected.

Moved python-capdl-tool into subdirectory