v3.18.0

ModelingToolkit v3.18.0

Diff since v3.17.0

Closed issues:

• build_function is allocating for StaticArrays (#559)

Merged pull requests:

• CompatHelper: bump compat for "Latexify" to "0.14" (#561) (@github-actions[bot])
• Add ControlSystem for Nonlinear Optimal Control (#562) (@ChrisRackauckas)
• Direct compilation of C function from CTarget via GCC (#566) (@ChrisRackauckas)
• converting to C tutorial (#567) (@ChrisRackauckas)