technion compilation 236360 retake

• this is my second time taking this course (in the 2021 spring semester).
• on my last attempt (2021 winter semester), i put a lot of code inside the .lex/.ypp files, which caused many bugs
• this time, i have 0 memory leaks, and no bugs (hw4 is a dry exercise):
  
• i fixed the bug on hw1 after submitting it (i only supported uppercase hexa chars)
• to use flex/bison on windows, install cygwin/wsl and the flex & bison packages. see: https://cmake.org/cmake/help/latest/module/FindFLEX.html
• in every semester, a different feature is added to the compiler. this semester, it was a switch-case statement