[julia mode] added additional operators and fixed 'in' keyword

The following operators are recognized, which I think are all the ones from https://github.com/JuliaLang/julia/blob/master/src/julia-parser.scm#L1, but I may have still missed some. 

Also 'in' is now classified as an operator instead of a keyword. 

#operators
|=
&=
^=
\-
%=
*=
+=
-=
<=
>=
!=
==
%
*
+
-
<
>
!
=
|
&
^
\
?
~
:
$
<:
.<
.>
<<
<<=
>>
>>>>
>>=
>>>=
<<=
<<<=
.<=
.>=
.==
->
//
in
...
//
:=
.//=
.*=
./=
.^=
.%=
.+=
.-=
\=
\\=
||
===
&&
|=
.|=
<:
>:
|>
<|
::
x ? y : z