Removed incorrect constraint requiring base flow to be 2D2C for SM.

Move executable name override to TestData class.

This MR moves the parsing of a command-line override of the executable to use for a test into the TestData class so we do not expect an tag in the .tst file.

See merge request !595

Fix problem in QuadExp with different number of points per direction

This fixes a few bugs in `QuadExp`, which prevent simulations using quads from working when the number of points is not the same in both directions.

See merge request !607

Fix/compressed io seg curved

Provide a fix to issue #24 where extracting a 1D manifold from a 2D mesh did not contain curvature when the file was in compressedIO format. This was due to an incorrect reference to a face map rather than an edge map. 

See merge request !619

fix lapack call

This fixes a small bug in the lapack call for eigensolve of full nektar matrices. Previously it was not assigning enough room in memory for lapack

See merge request !610

Fix FieldConvert processing of partitions in serial

This MR makes two changes related to using FieldConvert on individual partitions in serial:
- Fix the call to PartitionMesh inside OutputInfo. This was previously using `PartitionMesh(false)`, when the first parameter should be the number of partitions.
- Force FieldConvert to use the `forceoutput` option when using `procid`. If this was not done, whenever `procid != 0` the output would be automatically skipped. 

See merge request !612

Fix MultiLevelStaticCond with periodic BCs

This should fix issue #21, regarding the use of MultiLevelStaticCond with periodic boundary conditions in parallel. Basically, this involves forcing all periodic boundary conditions to be on the last level of the static cond. I expected doing this only for the dofs connected to other partitions would be enough, but apparently it is not since it leads to a segfault in one of the cases I tested.

See merge request !614

Force InputFld to update fielddef

This forces InputFld to update fielddef after loading the expansions, instead of only doing this when range is specified. This is necessary because the number of partitions from the original file might not be the same as the number of processes being used in FieldConvert, causing the fielddef obtained from Import to contain extra elements.

For example, when converting a serial fld to a parallel format using
```
mpirun -np 8 FieldConvert file.xml file_serial.fld file_par.fld
```
the current implementation causes all 8 partition files from file_par.fld to contain the whole field.

See merge request !611

Fix for assembly map array initialisation bug.

This MR fixes a bug in the CG assembly map which incorrectly initialises the local coefficient array if performing an in-place assembly.

See merge request !598

Initial instructions on how to build the documentation and tutorials.

This MR expands the user guide to describe how to build the user guide, doxygen and tutorials.

See merge request !596

Fix for clang 7.3 in compiling metis

This MR fixes an issue in compiling METIS on Clang 7.3, which ships with the latest OS X Xcode.

See merge request !603