Path: End in Separator

[ax3l]

Enforce path attributes end in separator.

This will throw a clean formatting error.

Related to #43

[RemiLehe]

The PR is OK ; however this will typically print:

Error: Attribute meshesPath in some_file.h5 does not satisfy format ('meshes' should be in format '^.*\/$')!"

To most users (not used to regex), this might look strange...

Any easy suggestion to improve this?

[ax3l]

Yes! We could generally add a hand-written error message for such places! :) #46