v6.4.2

ModelingToolkit v6.4.2

Diff since v6.4.1

Closed issues:

• IfElse is broken from v6.3 (#1210)
• Problem using inputs in structural_simplify (#1211)
• @register-ed function with vector arguments fail check_units() (#1218)

Merged pull requests:

• Handle conditionals & comparisons correctly in unit validation. (#1213) (@lamorton)
• Use iteration instead of vector indexing (#1214) (@lamorton)
• Add Integral Operator to get_unit (#1219) (@ashutosh-b-b)
• Fixes #1218 issue with get_unit(Vector{Num}). (#1220) (@lamorton)