Add --color=yes as argument to get color output

[dhoegh]

It would be nice if the output in IJulia allowed for colors, for an example for the output of @code_warntype. @code_warntype gets colors if --color=yes is added as a startup argument in the ipython_config.py file, but it do not color the error messages which also would be nice.

[stevengj]

Doesn't julia --color=yes use ANSI escape codes for colored text in a terminal? How are these supposed to work in the browser? (They would work in the IPython console front-end, presumably, but hardly anyone uses that; the most important things are the notebook and qt front ends.)

[dhoegh]

println("\x1b[31m\"red\"\x1b[0m") seems to print red, you can also see:
http://stackoverflow.com/questions/16816013/is-it-possible-to-print-using-different-color-in-ipythons-notebook

But it seems to be very dark colors compared to the terminal.

[Carreau]

I wouldn't rely too much on ANSI for in-browser color support, it works but is known to have edge cases,
especially when converting with nbconvert to format that need to strip coloring.

ANSI coloring is also relatively painful when dealing with dark and light background.
It can be worked-around-ish by mapping dark-[a-color]-to light-[same-color], and lots f things like that,
but is always wonky.
It would be much nicer is something like the display system was use to send real html
to the page with actual classes (much like bootstrap) than convey semantic information.

IHaskell do a great job at that, having even a representation for unshowable types.

[IainNZ]

@stevengj does Julia "know" that IJulia is consuming its stdout? Is there some way print_with_color can do something different to the ANSI codes on that basis?

[stevengj]

@IainNZ, one option is to do something like how readline is implemented.

This is a bit hacky, though. Ideally, I'd like the warning to call display on an object with writemime methods for text/html etc so that colors would appear automatically for appropriate backends.

[KristofferC]

Closed by #470?