0.512

Analysis changes

• Improve refinement support for unions, in particular it's now possible to implement tagged unions as a union of tables where individual branches use a string literal type for one of the fields.
• Fix string.split type information

Runtime changes

• Optimize select(_, ...) to run in constant time (~2.7x faster on VariadicSelect benchmark)
• Improve debug line information for multi-line assignments
• Improve compilation of table literals when table keys are constant expressions/variables
• Use forward GC barrier for setmetatable which slightly accelerates GC progress

CLI changes

• Repl now uses _PRETTYPRINT if available to print expression values instead of print

Community contributions

• luau-analyze: Add support for reading source code from stdin by @vladmarica in #325