GnuCOBOL: Implement Initial Object-Oriented Programming Support

GnuCOBOL currently has no support for the Object-Oriented Programming (OOP) features defined by the ISO standards ISO/IEC 1989:2002 through ISO/IEC 1989:2023. Object-Oriented (OO) code currently leads to syntax errors due to lack of parsing support. The project aims to build support for parsing all OO syntax, and for a subset, also implement AST and codegen support to get a minimal working prototype of calling class methods through objects. Support for complex OOP features like method overriding and single inheritance will also be implemented. Multiple inheritance, method prototypes and parameterised classes are excluded for now. As a result, future releases of GnuCOBOL 3 will be able to parse OO code and report a simple error message about the pending feature. GnuCOBOL 4 will introduce the new paradigm to users. It will be able to generate working binaries for OO code and handle complex features like method overriding and single inheritance. The project will help bring GnuCOBOL closer to being compliant with ISO standards for OO COBOL and establish it as a significant choice among institutions looking for a free COBOL compiler with OOP support.