Added more simulations tests

[miguelmaso]

The simulation files have the following properties:

• The functions are self-contained and should work as an example
• The functions accept named parameters, such as writevtk and verbose
• The functions return some value that allows to perform a check

Helper function added to HyperFEM:

• Io.jl -> projdir Return a folder relative to the HyperFEM dir
• Io.jl -> filedir Return a folder relative to the current file

Let's see if the tests and benchmraks are fine

[miguelmaso]

Benchmarks will be failing until this PR is merged.

Reason: I've modified a function in test/data/ replacing argument write_vtk by writevtk. Hence, when comparing versions, the old one is inconsistent.

[miguelmaso]

@jmartfrut ready to merge