Added empty string regex test.
Fixed syntax in added empty string regex test.
Added simple regexp test.
Added test unapply regexp.
Added simple test for processing string with map method.
Added simple test for processing string with for method.
Added test for indexed access to character.
Added test for replacing by pattern.
Added test for improving String with own method.
Improved String moved to separate object.
Added test for parsing int from string.
Added test for numeric types casting.
Added test for increment/decrement.
Added test for BigInt.
Added isPrintable method.
Added test for generating random values.