Imp: Mesh building error reporting

[tngreene]

Here is what we need to cover and report

• [ ] Improper VT directive (which value)
• [ ] Improper IDX/IDX10 directive
• [ ] VT without IDX using them
• [ ] IDX without VT
• [ ] TRIS going beyond the end of the table

All except TRIS should result in ParserError, bad TRIS directive should simply be a warn and continue