'static foreach' chapter and more

[Ali Çehreli]

I've made some online improvements to "Programming in D" since September 
2017.

   http://ddili.org/ders/d.en/index.html

NOTE: The copies of the book at hard copy printers are not updated yet. 
If you order from Amazon etc. it will still be the OLD version. I need 
some more time to work on that... Also, only the PDF electronic format 
is up-to-date; other ebook formats are NOT.

* The code samples are now up-to-date with 2.080.1

* Digit separator (%,) format specifier: 
http://ddili.org/ders/d.en/formatted_output.html#ix_formatted_output.separator

* Stopwatch is moved to module std.datetime.stopwatch

* Replace 'body' with 'do'

* Text file imports (string imports): 
http://ddili.org/ders/d.en/mixin.html#ix_mixin.file%20import

* First assignment to a member is construction (search for that text on 
the page): 
http://ddili.org/ders/d.en/special_functions.html#ix_special_functions.this,%20constructor

* static foreach: 
http://ddili.org/ders/d.en/static_foreach.html#ix_static_foreach.static%20foreach

Ali