SimpleXLSX: Rename a variable, missed in [5c24535]
EvalMath: Fix return type in inline docs
"Edit" screen: Remove unused variable, missed in [b08c4a3]
ExcelReader: Add some missing class properties, turn some class properties into local variables, fix inline documentation, and fix white space
CSSTidy: Add missing class properties, remove an unused function parameter, make a protected property public
EvalMath: Add missing variable names in inline docs
EvalMath: Be less strict in the equality comparison, as the variable type may differ
EvalMath: Add boolean functions for negation ("not"), conjunction ("and"), and disjunction ("or")
Unit Tests: Extend some unit tests for the EvalMath library and fix the inline documentation