std.d.lexer: pre-voting review / discussion

[Brian Schott]

I got some time to work on the lexer this evening. Changeset 
here: 
https://github.com/Hackerpilot/phobos/commit/9bdb7f97bb8021f3b0d0291896b8fe21a6fead23#std/d/lexer.d

The DDoc page has moved here: 
http://hackerpilot.github.io/experimental/std_lexer/phobos/std_d_lexer.html

* There are a few more unit tests now
* bitAnd renamed to amp
* slice rename to dotdot
* Much more cross-referencing in the doc comments
* Start line and column can be specified in the lexer config