Better Error Messages (#14)

* Changed how errors display, now include line number and ensure all toml.io links work
* Updated all errors that could occur during parser
* Removed _nsmerror in utf-8 validation and replaced with standard error handling
* In UTF-8 escaping, show the actual hex escape in the error message to make things easier
* Encoder shows which key failed and displays datetime errors nicely
* Added filesize and nesting depth options.

Author: FourierTransformer