Improvements to rule and crisp expression parsing

[brownag]

This ensures that all primary, ready-to-use rules can be parsed.

• Updates rules, evaluations, properties datasets to include dataafuse field (ready-to-use flag)
• Adds support for IsNull curve type
• Many improvements for syntax edge cases in crisp expressions

This update has been tested on all current primary rules that are marked ready to use. There may still be some cases that need to be tested for parity with NASIS, especially for use of wildcards in equality, MATCHES, IMATCHES but there all conversions of crisp expression to R function should now at least result in valid R syntax.