Improve error messages

[TheElectronWill]

I see two big areas of improvement:

• Parsers: show the erroneous line (and maybe even its content!)
• ObjectConverter: detect when the types mismatch, for instance when the user tries to convert a table into a String because it incorrectly typed String instead of its class. See e.g. Error Thrown from ObjectConverter when Trying to Populate a String Field #103