v1 API changes

[brandonchinn178]

Breaking changes to release with v1, blocked on #4:

• Rename Text constructor to String in Value
• Add Data.Default instance for format types (re-export def)
• Make format fields non-Maybe
  • We actually can't do this because the "default format" is stateful - e.g. add indentation as you go deeper into a child node
• Nest format types under ext field (e.g. NodeExtension)
• Add Span to all ext types with startLine/startCol/endLine/endCol
  • Default = all fields set to 0 or an impure error
  • Add parseWith/parseFileWith that takes settings, currently has filepath and includeSpans (default to "" and False)
• Remove the non-record-dot selector functions
  • There are already lots of options here (OverloadedRecordDot, NamedFieldPuns, RecordWildCard, record pattern matching). Just remove these. People could always define it themselves if they really want to