Please add ability for sticker to emit more than one signal. That will allow to send multiple cargo types to one road and others to other, and that would make crossroads/junctions much more simpler to manage.

I've got too impatient so...
Addition for the mod author and anyone who wishes to have multisignal stickers, here's the diff patch to be applied to the code:
https://pastebin.com/gdy2GaUU

Publish it as a separate mod, the author of this mod will never hear you.

By the way, where should I add/replace this code to get such a sticker?

It would be great to have a sticker that passes carts through AND and another sticker for OR.

A simplified description of the diff format:
Line 9 specifies the file in question. "a/" means "before changes" and "b/" - "after"
On line 10 "-1110,10" denotes a block of code that was starting from line 1110 and it's length is 10 lines. "+1110,10" means the new state of the block is starting on line 1110 and it's length is 10 lines.
Next you see a block of code. Lines that have no "-" nor "+" in front of them are not changed. Lines with "-" show code which was there before the change, and "+" shows how code is now looks like changed. Basically, "-" == "removed", and "+" == "added".
Line 25 says "-1724,23 +1724,32", which is "following block of code started at line 1724, and was 23 lines long. Now it's starting at the same line, but is now 32 lines long". And again, "-" marks what is removed, and "+" marks what is added.

Then on line 69 begins diff of a different file, "a/" == "before changes", "b/" == "after", line 70 can be ignored if you're not using/don't know how to use git, and all following lines already explained.

Now, regarding a separate mod — nah, author have been active elsewhere, so the chances are he'll revisit this mod and maybe make an update. If not, I'd rather wait till Factorio 1.0 release, which August 14th.

Right now the change I did works as OR sticker, but AND is a good idea. But at the moment I'm more interested in making a "full-unload stop" to remove the need of having a constant combinator at each unload stop.

This is similar to the instructions for the program. .diff is intended to be run by a special program?

Yes, it's used by version control systems, like git, svn, mercurial. But if you're not familiar with them, it's better to do it manually than trying to figure out the git... I'm not sure even Linus Torvalds, creator of git, understands it completely :D