Fields with some symbols are not supported

[magsilva]

Fields with some symbols are not supported. For instance, I'm trying to create a field named 'e-issn'. For previous versions of JabRef, it works just fine. The BibTeX file format does also support it. However, JabRef does not allow white space, (, #, }, {, ), (, ~, ^, &, -, ", ', `, ', . Some of those symbols shouldn't be accepted, but '-' is completely ok for field name.