v9.9.0

ModelingToolkit v9.9.0

Diff since v9.8.0

Merged pull requests:

• Fix _varmap_to_vars, re-enable dde.jl test (#2545) (@MasonProtter)
• Document and export continuous_events and discrete_events (#2567) (@MasonProtter)
• feat: implement SII.remake_buffer for MTKParameters, fix bugs, add tests (#2570) (@AayushSabharwal)
• Empty events should be empty (#2582) (@YingboMa)
• fix: fix varmap_to_vars for variables with unspecified size (#2586) (@AayushSabharwal)
• Fix tearing_reassemble for under-determined systems (#2587) (@YingboMa)
• refactor: remove undefined export initializesystem (#2588) (@sathvikbhagavan)

Closed issues:

• structural_simplify does not seem to include dae_index_lowering anymore (#2417)
• Re-add DiscreteSystem (#2461)
• Dropped unknowns with non-fully determined structural simplifications (#2515)
• MTK 9 fails to simplify u0map with DDEProblem (#2543)
• Error with MTKParameters and Dual Numbers (#2571)