Fix bug in DriverModifiedArnoldi

This fixes a bug in ModifiedArnoldi, which may cause the solver to exit with
```
Fatal   : Level 0 assertion violation
Unrecognised value.
```
as recently reported in nektar-users.

The problem happens because the iteration could be marked as converged when the number of vectors available is lower than `nvec`.

See merge request !608

Fix bug in Homogeneous1DTrans

This fixes a small bug in `ExpListHomogeneous1D::Homogeneous1DTrans`.

I think the particular case where this was wrong is not used anywhere, so it is very likely that nothing will change.

See merge request !599

Updated to extract directory of libccmio.a

Updated the ThirdPartyCCM.cmake file to add in Link directory and use the get_Filename_component to obtain the directory path if the library is found. This therefore allows the libccmio.a to be correctly linked from a third party location where as previous it was only compiling if the .a files were copied to the dist/lib directory. 

See merge request !600

Add option to turn off https support to solve CMake SSL woes

This MR adds a `THIRDPARTY_USE_SSL` option to enable/disable HTTPS support and fix #22, since some versions of CMake (including compute nodes and cx2 at least) are not compiled with SSL support, causing obtuse failures. The default is set to off to allow the greater range of systems to work out of the box.

See merge request !602

Increment to version 4.4

Increment version.

See merge request !587

Feature/substepping

Introduction of a working version of a substepping version of the Incompressible Navier Stokes solver. 


See merge request !553

Issue warning and ignore empty XML tags

This MR modifies the session reader logic to ignore empty XML tags which would otherwise replace non-empty tags. This prevents, for example, the empty CONDITIONS section generated by NekMesh from displacing the user-provided conditions if the user condition file is supplied before the mesh file on the command-line.

@ssherw: This has been tested locally and everything passed. Just running through buildbot now.

See merge request !581

Tester updates for testing tutorials

The MR adds an option to the Tester code to allow the executable specified in the .tst file to be overridden on the command-line. This is to allow the use of executables which lie elsewhere in the build tree, not just in the directory containing the Tests directory.

It also fixes support for input files to be located in a different directory to the test file itself. It would previously fail if the list of dependent files included a relative path to a file in a different directory.

Finally, there are also a couple of tweaks to the submodule so git ignores it when things have changed.

See merge request !580

Add OS X packaging for binaries

This MR adds packaging for OS X.

See merge request !544

Updated Set_Rhs_Magnitude to use a predefined weight. Also introduced a switch not to use the weight when running the Multi-Level static Condensation

updated the Set_Rhs_Magnitude method to only use a maixmum of 1000 counter steps in its weighting. The use of a member variable instead of a static int has also changed how the magnitude and therefore tolerance is evalauting requiring a change in the values in the .tst file

tags which replace non-empty tags.