Array Expressions

implement array_agg and array_to_string (#9)

- implement ARRAY_AGG
- implement ARRAY_TO_STRING

CONCAT & COALESCE comparable

COALESCE & CONCAT can be compared (#8)

- COALESCE(3|4|5) & CONCAT(3|4|5) can be compared
- remove AnyComparison as control flow works now
- CONCAT must now all be same underlying type

Arithmetic Added

Added Arithmetic Functions (#7)

* arithmetic support
* spelling changes

Conditionals

• if/else and switch (no if without else)
• EmptyExpression

Support for `Group`/`NestedColumn`

• NestedColumn/Group support for key path access to jsonb_extract_text_path

AnyCompareExpression

• AnyCompareExpression for type erased expression
• && for compare
• Either (if/else & switch) for builders

Date Updates

• Multiple date types (PSQLDate, PSQLTimestamp) can be in PSQLRange
• Public PSQLDateType protocol for custom date conformances

`IS`/`IS NOT` & Coalesce Additions

• Rename XXXExpressible to XXXExpression
• Rename PrimativeSelection to RawValue
• Add IS/IS NOT for comparisons (should be used for NULL checks)
• Add more COALESCE options like CONCAT
• CompareOperator now a struct so can be extended by 3rd parties

Initial Release

Whew, here we go. Check the README for info