Fix the compilation warning messages

[itssamuelrowe]

JTK was created to write a compiler for a language that I designing. It's been three years since I started working on the project. Given my schedule, I am not able to work on both Zen and JTK. For the most part, JTK seems to work fine. However, the compiler generates a plethora of warnings during compilation. I have disabled warnings in CMakeLists.txt file. It would be really helpful if someone could help me fix the warnings.