update to codemirror-3.2.0

- Used http://codemirror.net/doc/compress.html to
  obtain a compressed js with builtin d mode.
update NCEG operators

https://github.com/D-Programming-Language/dmd/pull/2844
remove NCEG specs
add interfaces to style guide

Interfaces should PascalCased, like classes.
Merge pull request #446 from gittywithexcitement/patch-1

add interfaces to style guide
Merge pull request #423 from MartinNowak/updateCodemirror

update to codemirror-3.2.0
fix Issue 11711 - Add __traits(getAliasThis)
Merge pull request #447 from 9rnsr/fix11711

Issue 11711 - Add __traits(getAliasThis)
Merge pull request #445 from MartinNowak/nceg

remove NCEG specs
Add note for lower case suffix 'l' and allow it in lexing level.

Related: Issue 11759 - Poor error message trying to use lowercase L in literal
suffix.
Merge pull request #448 from 9rnsr/fix11759

Add note for lower case suffix 'l' and allow it in lexing level.
Update operatoroverloading.dd

In my browser the arguments are not properly displayed. Therefore, I changed them so they will be. For me it looks like this: 
    -a[b⊂, b⊂, ... b⊂]    a.opIndexUnary!("-" )(b⊂, b⊂, ... b⊂)
    +a[b⊂, b⊂, ... b⊂]    a.opIndexUnary!("+" )(b⊂, b⊂, ... b⊂)
    ~a[b⊂, b⊂, ... b⊂]    a.opIndexUnary!("~" )(b⊂, b⊂, ... b⊂)
    *a[b⊂, b⊂, ... b⊂]    a.opIndexUnary!("*" )(b⊂, b⊂, ... b⊂)
   ++a[b⊂, b⊂, ... b⊂]    a.opIndexUnary!("++")(b⊂, b⊂, ... b⊂)
   --a[b⊂, b⊂, ... b⊂]    a.opIndexUnary!("--")(b⊂, b⊂, ... b⊂)
Which does not seem to be right.
Update operatoroverloading.dd

Fixed typo: then -> than. Also clarified sentence.
Update operatoroverloading.dd

Replaced weird b⊂, b⊂, ... b⊂ by b1,b2,...,bn. 

Same as before. Please check, if the changes are correct.
Merge pull request #451 from ralphtandetzky/patch-17

Update operatoroverloading.dd
Merge pull request #450 from ralphtandetzky/patch-16

Update operatoroverloading.dd
Merge pull request #449 from ralphtandetzky/patch-15

Update operatoroverloading.dd
Update operatoroverloading.dd

Improved formatting by putting some code within text inside "$(D ...)".
Merge pull request #453 from ralphtandetzky/patch-19

Update operatoroverloading.dd
update the compiler dowload link

1.http://dlang.org/download.html
we see that the version is 2.064.2

2.http://dlang.org/dmd-linux.html
when we click the 'Download D Compiler', go to this page
http://www.digitalmars.com/d/download.html
the version is 2.063.2