Custom Markdown for PHP handling new lines

I need custom Markdown library for PHP which converts new lines to <br/> without the need to put double space on the end of the line, kinda like here on SO. I've been looking on the web but without success. I know I could just am开发者_运维技巧end standard library but my regex skills are none.

Does anybody know about such library in existence or know how to change default behaviour easily?

EDIT: Dumb me, SO does not work this way, it appears to be standard Markdown behaviour. However such functionality is being used on github.com.

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One way is to use Text_Wiki, enabling the newline rule. I suspect other wiki parsers have this feature, maybe just not enabled by default.