Ensure ACY files are present for every module

CurryDoc fails when the initial call to the frontend does not generate ACY files for all dependent modules. With this patch, CurryDoc checks for an ACY file before generating the documentation for a module. If the file is missing, it calls the frontend to generate it.

See merge request !1

CDBI: eDescription renamed to e_CDBI_Description to avoid name clashes with ER model, string with null values: Maybe type omitted