* general review / remove duplicated tests

* keyword: package
* keyword: protected
* keyword: public
* keyword: export
* keyword: debug
* keyword: synchronized
* keyword: private
* keyword: unittest
* keyword: struct (anonymous)
* keyword: function
* keyword: asm
* keyword: char (test that it realy is unsigned)
* keyword: wchar
* keyword: dchar

* extend tests for design by contract

* extend tests for inner functions

* operators

* custom operator implementation

* Embedded _ in numeric literals
	18_446_744_073_709_551_615 / 18446744073709551615

* X strings
	D has the x string, where hex data can be simply wrapped with double quotes, leaving the whitespace intact:
	x"00 0A E3 DC 86 73 7E 7E"

* char escapes
	\U , \u , \x
	
* module initializers & ?destructors?
	module foo;
	
	static this(){
		... initialization code ...
	}

* comments
	/* */ // /+ +/