Remove compile order check

MeshIO.hh enforces that MeshIO.hh is included before any mesh type is included. I don't know why that is. I removed that check and in the unittests I included MeshIO.hh after the mesh types. Everything seems to work fine.

I don't remember why this was enforced. I'm not sure if it's worth the risk removing it.

I don't know if this is a problem for many people, but for me it caused a headache more than once.

In a large project with some headers including MeshIO.hh and some including a mesh type it can be very hard to find a compilable include order for multiple of those files. Especially if MeshIO.hh is not included directly but only after a chain of several headers.

A common style guide seems to be to order includes alphabetically. With the compile order check in MeshIO.hh this convention may be impossible to follow.

I don't know what trouble the wrong include order may have caused in the past so it is hard to say whether the arguments above are worth taking the risk...

mentioned in merge request !162 (merged)

closed

I merged a warning instead of removing the check. If that warning does not create reports, we will remove it.