added CodeGenerator class
added implementation of checkVariableDeclared and checkFunctionDeclared
removed compile errors
completed expressions map
implemented isInSymbolsTable() and parametersMatch()
removed syntax tests and corrected minor errors in official test
added SemanticChecker to source files list
added checkImport, checkDimensions and corrected for/switch control functions
added semantic checks for main function and continue/break statements
corrected error in exitFor() function
added function enter/exit scope and a check for variables
added addSymbol() functions and checkers
added auxiliar symbol data and added function entries into symbols table
corrected isModifiable() and printSymbolsTable()
added code to build symbols table
added checks for required return statements
added only-run script
added checks for undeclared variables in assignments and some corrections
added checks for already declared variables
added type info to already-declared message