Ddox: support assert to writeln rewrite

[wilzbach]

There's already some very naive support to rewrite assert's statements to writeln function calls for the ddoc build.
This just adds extend the RegExp for ddox.

This approach itself is pretty limited and of course it would be better to do this during compilation (e.g. as a plugin for ddox) and not via RegExp in Js. Moreover, the RegExp itself might catch some false positives and also doesn't support other common operations like equal or a plain assert.

So this is intended as temporary solution until someone has more time to invest into a proper solution.

Btw another reason which makes this complicated is that there are two code boxes (the editor and code highlighted produced by ddoc/ddox) and one can only edit the plain source code of the former. At the moment "reset" hides the editor and shows the original code from ddoc/ddox, but one could argue that there's no point in keeping this code box generated by ddoc/ddox

[wilzbach]

Current ddoc behavior - the pattern assert(a == b); is automatically rewritten to writeln(a); // b:

https://dlang.org/phobos-prerelease/std_algorithm_searching.html#.minElement

Corresponding ddox page:

http://dtest.thecybershadow.net/artifact/website-df837d199d2c48d73acc50a0d6ed8a372e27a872-4099e695caf15988d1389a039504cffd/web/library-prerelease/std/algorithm/searching/min_element.html

[andralex]

This is a bit odd. But heck let's try it.

[andralex]

dat regex

[andralex]

conflicts please rebase

[wilzbach]

conflicts please rebase

rebased ;-)

[wilzbach]

conflicts please rebase
rebased ;-)

(merging as rebased and approved)