Fix doxygen.config for spaces in path
Add dax::internal::GetNthType helper class template

Add a GetNthType template to lookup the elements of a type sequence.
For now support only function types.
Add dax::internal::Members class template

Add a class template that offers storage of arbitrary "members" that can
be indexed programmatically by compile-time constructs.
Add dax::internal::Tags

Add a class template to manage sets of compile-time tags.
Add dax::cont::arg::ConceptMap

Forward declare a class template whose partial specializations will
define how to map concrete value types to abstract concepts named as
parameters of worklet control environment signatures.
Add dax::cont::sig::Arg and dax::cont::sig::Tag

Create namespace "dax::cont::sig" to hold names to be referenced from
worklet ControlSignature and ExecutionSignature declarations.
Add dax::cont::arg::Field concept and mapping for float constants
Add dax::cont::internal::Bindings

Add a class template to hold argument values passed to a worklet
invocation in the control environment and mapped to the concepts
declared in the ControlSignature.
Add dax::exec::arg::Bind and dax::exec::arg::BindDirect

Forward declare a class template to lookup for a given work type the
type representing an argument declared in a worklet ExecutionSignature
when bound to a specific value passed through the control environment.

Add one specialization to bind direct references to control environment
arguments with a compatible index space.
Add dax::exec::internal::Functor

Add a class template to construct a functor to be scheduled in the
execution environment to invoke a worklet given arguments bound to the
ControlSignature.
Add dax::cont::arg::Topology concept

Also add corresponding Domain/Point/Cell signature tags.
Add signature concept, tag, and placeholder names to work types

Provide relevant names from dax::cont::arg and dax::cont::sig to
worklets deriving from WorkletMapField and WorkletMapCell.  This will
allow direct references to the names in ControlSignature and
ExecutionSignature declarations.  While at it, provide in each work type
class a "WorkType" typedef naming itself.
Add dax::cont::internal::FindBinding

Add class template to search through the control environment bindings of
a worklet invocation to find an argument bound to a specific concept.
Add dax::exec::arg::BindCellPoints for WorkletMapCell

WorkletMapCell schedules for cells so indexes refer to cells.  If a
Field argument in the ControlSignature is tagged as a Point field then
it cannot be directly indexed.  Instead we need to use a Topology
argument to map the cell index to point indexes and pass the field falue
from every point to the worklet in the execution environment.  Add
BindCellPoints to represent this operation.  Add a dax::exec::arg::Bind
specialization for WorkletMapCell to choose between BindDirect and
BindCellPoints based on the parameter tags.
Add dax::cont::arg::Field  mapping for integer constants.
Add dax::Tuple, dax::Vector(2,3,4) and dax::Id3 to FieldConcept.

We can now pass constant values of all the basic types in dax
to the execution env.
ConceptMaps are associated with different domains. If a concept map
says it is part of the Points domain for example, that means we
should be able to ask for its size on the point domain.

This size is important as it is used to determine the number
of kernels we should schedule.

For now all constant field domains are part of only the
root domain, meaning they have no length or size.
Add to worklet types the primary domain.

This domain will be used to determine the number of elements that
need to be scheduled by the scheduling code.
Add dax::cont::arg::Field mapping for ArrayHandles.

We convert array handles to field portals. This requires that the
scheduling code will have to tell each array handle that has the
output tag what size to allocate.

In the future we have to also add an ability to all concept maps
to support bringing results back to the control env.
Add in the infastructure to schedule abitrary worklets.

This just creates the exec fields needed for the worklets to execute.
It doesn't actually execute the worklets. The outstanding issues
are that we need to find the current device adapter and
saving fields with the Out tag.

We also need to convert the header to use boost preprocessor macros
to handle abritrary number of arguments.