Bug#588864: Add syntax highlight file for scilab

[Sylvestre Ledru]

Hello

The current scilab.lang file on the Scilab website is outdated. 
I wrote a new one from octave's and sent it upstream:
https://bugzilla.gnome.org/show_bug.cgi?id=630404

Until the new upstream release is available and uploaded in Debian, I
can create a new package for this. 
Would you like a new packages with this ?

> Also, add the relevant mime types.
What do you mean here ?

Thanks,
Sylvestre