This PR contains two big changes:

Lualib files are now modules

• Lualib sources now use import/export
• Importing lualib functions now works the same as importing modules (in generated lua)
• Inlining lualib files is unchanged, except the imported functionality is now local instead of global
• The lualib dependency tree is no longer manually maintained, instead it is automatically generated during the lualib build.
  • The lualib dependency tree is distributed in our package as a json file.
• Lualib output is generated with a tstl plugin to minimize lualib-generation-specific code in the main transpiler.

Plugins now provide beforeTransform and afterEmit hooks

To generate the required lualib files we used a plugin that required some extra hooks. Because of this we introduced two extra TSTL plugin functions:

beforeTansform

{
beforeTransform?: (
    program: ts.Program,
    options: CompilerOptions,
    emitHost: EmitHost
) => ts.Diagnostic[] | void;
}

This function on the plugin is called after gathering the TypeScript program and options, but before starting the transformation process. This can be used to set up stuff in the plugin, or to modify the program/options that the transpiler will act on.

afterPrint

{
afterPrint?: (
    program: ts.Program,
    options: CompilerOptions,
    emitHost: EmitHost,
    result: ProcessedFile[]
) => ts.Diagnostic[] | void;
}

This function on the plugin is run after the printing of Lua has completed. It provides the output array as one of its parameters, which can be used to modify the final output before finishing the emit.