Update to clang-format-5 and reformat the codebase 

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This is required as Qt4 is not completely C++11 compliant.  I think that these will no longer be needed when we move to Qt5.
Should only be required for files up to and including API.
Refs #7284

Refs #9059

If we don't then we get a crash in the FileLoaderRegistry that tries
to cast to an incorrect type.

Refs #8177

This avoids having to declare a new interface when a new loader type
is added.

* Rename HDFDescriptor to NexusDescriptor
* Rename {HDF,NonHDF} -> {Nexus,Generic} in FileLoaderRegistry
* Rename DECLARE_HDF_FILELOADER_ALGORITHM ->
  DECLARE_NEXUS_FILELOADER_ALGORITHM

Refs #7461

This better encapsulates the file checking so that other places don't
have to worry about the desciptor stuff.
Refs #7263

Also added runtime checks to the subscribe method. This allows it to static
cast at runtime when checking rather than a more expensive dynamic cast.

It appears that we can't start the FrameworkManager during static
initialization or the destruction of the FrameworkManager instance gets
instance gets confused.

The FileLoaderRegistry can now be asked to search its list of loaders
for the best that matches a given file. It passes along a *Descriptor
object to minimize the number of times the file is opened.

Refs #7263

and also defines two types of loader, NonHDF and HDF.
Refs #7263

Currently based on string names.

but users might use it too. Wanted to make a separate ticket for this but trac is down

Refs #3724: Pulled wiki description text from the wiki site and added in algorithms' header file with special tags. The auto_wiki.py script can retrieve the text to generate the wiki page fully.

Refs #3507. Full-move to MVP. Sorry for large checkin, but these things are all dependent and cannot have partially working GUI code.