Compatibility with ACT R library about pympi

[dopefishh]

Extra spacing before closing XML tags signals a fragile XML parser from ACT's side. However, I'm not opposed to generating stricter XML without this spacing as it doesn't change the semantics of the file.
Increasing the version can be done, but we have to make sure that the generated file really is 3.0 compliant. Since the major version is increased, I assume there are some backwards incompatible changes between 2.x and 3.x.
The specification can be found here: https://www.mpi.nl/tools/elan/EAF_Annotation_Format_3.0_and_ELAN.pdf
In a previous issue we found that it probably is compatible though (#29).

So in short, yes please, I'm would be happy to accept merge requests for this.

[lucientisserand]

Totally agree, when I have time I will have a look into the differences between 2.8 and 3.0 before trying to propose something (still a beginner in python but learning by doing). Also maybe proposing ACT to treat space character cases as it's compliant with XML syntax.
In the meantime I hope some people may find the workaround useful it they are blocked.